Your boss has a real problem in this scenario since it’s technically illegal for a person to take the law into their own hands. He or she would face legal challenges regardless of whether they sell to the good guys or the bad. — Instead I would suggest selling to the cops and other law enforcement/ civil service officials.

Why not upgrade the fire fighters for example? Imagine rescue workers in flameproof mech suits rescuing people from the fires in California; or perhaps a park ranger being able to wrestle a bear rather then just shooting it.

The applications are nearly limitless, but your boss should consider applications outside the normal street crime scenario.

That being said, a police force in fully bullet proof mechanized tech armor being able to non-lethally subdue even the most dangerous gunmen would be pretty cool. No doubt this would go a long way to prevent a lot of the shoot-first-ask-questions-later incidents we hear about so much on the news.

Plausible deniability

Vigilantism is illegal, but our salesman isn't selling to vigilantes, no no.

He is selling self-defense equipment to concerned citizens. If you were assaulted in the street, wouldn't it be nice if you could just run away ... over the rooftops ... on Manhattan?

Other equipment can also be described as self-defense. Tazers, for example, for use on feral dogs only. It is clearly printed on the box that it is not for use against humans. If a customer breaks that rule, shame on the customer.

And that is not a bullet-proof suit, it is an extra sturdy motorcycling suit. Honest!

Laws generally won't forbid things that haven't been invented, so he can usually get away with selling things that aren't illegal, yet.

What people do with his wares is another matter. But isn't that like when somebody gets killed with a hammer? You don't go after the hammer manufacturer.

Your boss probably know some lobbyists too. They can be useful in delaying any laws that would cut into his profit margin.

You question is really similar to the problem some manufacturers in our world have to solve to stay in business.

If what you sell will remove competition and thus kill the market, just make sure you supply your product to both sides, so that there will be some sort of balance of power.

This has happened with nuclear bombs during cold war (atomic secrets sold by the very persons working to develop them), it happens on the weapons black market, where both sides of a conflict are supplied with weapons so that weapons merchants can thrive on the conflict. You are just going to be another actor on this stage.

And, at the end of the day, when one comes into your shop asking for a super-thing, how can you tell if is a good or a bad guy?

This is something that is actually legal in many areas, so this does not need to be kept hidden

There are a lot of places in the world where citizens are allowed to intervene in criminal activity, usually if they are witnesses of an ongoing crime or if the crime is severe. For example, many states in the US allow citizens to arrest felons if they witness the felony. Most of the types of crime heroes will be up against will probably be of this nature.

Double-dip on the profits by selling insurance to the heroes

Even though their activities may be legal, people still get dragged into court anyway, and sometimes they still get convicted even if they did not break the law. It's all about who has the better lawyers.

So you hire lots of great lawyers, not only for yourself but also to back the insurance you sell to the heroes. You could even insist that your non-black-market sales must be accompanied by a hero insurance plan or you won't make the sale.

Report on the events yourself, forming a small news group if you have to

If you report on the events yourself you can provide whatever spin on the situation you need, as is often done in media anyway. Make sure you have plenty of sensational headlines about your awesome heroes.

Some of your news can come in the form of social media that a billionaire should be able to push to go viral.

Create a network to aid the heroes

This part could come even before you get into the hero business so that it is already established to aid the heroes when you start those sales...

Start a campaign for neighborhood safety, the "neighborhood watch" of the next generation. Make an app for mobile devices that people would want to install to help their area which helps locate crimes. It would be similar to the batman scene in that one movie (sorry, not a batman fan and don't remember which one) where batman is getting data from devices all over an area to help him track people.

There's nothing stopping him putting his money into R&D. Essentially he's just joined the military-industrial complex, and become another arms dealer.

What kind of R&D is he thinking of though? Pretty much every area already has people working there. Either that, or (like Boston Dynamics) it's a neat idea with no market value. So he's always going to be playing catch-up. Most new companies form round a key first product, and he hasn't got one.

And then you have to actually look at whether Batman is practical. Why would you even do that? From a law enforcement PoV he's a disaster. From a military PoV he's one bullet or grenade away from just another corpse, because body armour doesn't stop everything. Rule of Cool doesn't work so well in real life.

He's chosen the wrong hero anyway. The definition of a hero is someone who saves the lives of other people without hoping for reward, right? If you've got that money spare, do something good with it.

No-one remembers Joseph Rowntree for what he did business-wise. Even his company name has gone, since it was bought by Nestle. But his charitable foundation continues to help people, and his name may well live forever.

No-one remembers Henry Wellcome for what he did business-wise either. But the Wellcome Trust is the reason we have gene therapies today, amongst so many other advances. Again, Wellcome's name will never be forgotten.

And more recently, Bill Gates. It doesn't matter whether you like what his company makes. The Bill and Melinda Gates Foundation is the reason millions of Africans will not die from diseases where the cures were well known but were not profitable for money-led medicine.

In terms of lives saved, Batman doesn't even come close.

Just point to him in the direction of dictionary.

Not one of those losers has decided to become Batman

"Decided to" not "are unable to". We have those "technical superpowers". Gas that can render people unconscious. Electric power that make muscles contract and people are unable to move. Hell, we even have jet powered bullets and non-lethal bullets. And for most of them (in the states) you don't need to be millionaire to have this equipment. You can go to shop and buy them.

In other words your boss want to go into self-defence industry.

Move to a more evil-friendly country

When bin Laden was forming al-Qaeda he didn't do this in the US or any other country with piddly things like laws. He did it in countries with weak, ineffective, extremist or corruptible governments.

You don't have to look far to find countries where you could locate your research, development and production lines. Parts of Somalia aren't even really countries right now. They are often ruled by the strongest overlord of the time. Which will be you very soon after setting up shop.

If the malaria and ebola become problematic for your workforce (and your bio-weapon researchers are too busy to make vaccines), you can move to any number of other countries where the government is fully corrupt. Give them a slice of the pie and enjoy immunity for as long as you keep somewhat below the radar.

What you save on taxes, you pay in bribes. Your bottom line remains the same. And with the monstrous amount of profits you will have rolling in soon, buy a large block of land and develop it to western standards for your workforce.

You hire a boatload of lawyers along with your boatload of scientists. You spin up shadow corporations, off shore accounts, subsidiaries with subsidiaries, which buy your bankrupted other subsidiaries and take their tech for unknown purposes. You incorporate where the law is malleable and can be bought for a reasonable price.

You do trial and error in lawless areas of the world, places where vigilantism is already the only law.

You check in on public opinion, make minor tweaks, rinse, wash, repeat.

You make sure that you are not traced back to any experiments that good poorly, while having your (also newly hired) boatload of PR people extoll the virtues of all the tech that is working out as intended.

You watch out for any politicians or social organizers, or NGOs that are taking note and starting to watch you more closely. You hire private investigators and hackers to make sure they know their dirty laundry is available and could end up out in the open if they're not careful.

You hire hitmen, and make inconvenient bloggers disappear.

In short, you become a super villain, and eventually your own technology will be used to take you down - if the do-gooders ever figure out it is you behind the whole thing.

But your boss will be too careful for that, I'm sure.

Well, I'm sure he's sure -- because every super-villain has a weakness, and with a rich one like this, that weakness is usually hubris.

Well this is world-building so it's a bit ambiguous; it's only illegal if there's a law against it.

And to that end I think the more widely useful your wares are the better. No one would outlaw hammers. It's a strange coincidence that the super-deluxe ultra-hammer 5000 is a great tool for robbing banks, but who would want to live in a world without hammers? Your top-of-the-line model might be a great crime-fighting kit that only millionaires can afford, but the starter model will really help out with your average Joe with his yardwork!

A bit of an aside, but I don't think you have to actually deal in any shady business yourself; if bad guys want your wares they'll come up with a way to get them. You just have to make sure the product doesn't get TOO regulated and studiously point out how you follow the letter of the law. Good PR, loyal fans, and a bit of lobbying are going to help.

He should just jump right in with the people who are already doing exactly this!

Most of the major weapons manufacturers in the world have various "super" organizations as their primary clients. Some of these organizations (commonly referred to as "governments") are the "good guys" and some are the "bad guys" (with divisions drawn along fairly arbitrary and shifting lines) but the weapons manufacturers make a killing by selling to both sides of every conflict (though not necessarily at the same time.)

These "super" organizations pay billions of dollars every year to equip hundreds of thousands of people with varying degrees of batman-like abilities as they see fit/can afford.

Just like in the comic books, clashes between these heroes and villains causes fallout that often kills hundreds of thousands, if not millions of innocent bystanders, laying waste to entire cities and forcing whole populations to abandon their homes and possessions or perish. Also, just like in the comic books, this little detail gets almost completely ignored by all "right-thinking" people of the world who are just glad to see good triumph over evil yet again.

Of course, for the most part these massive organizations are extremely jealous of the power they lord over the common folk, so his dreams of selling outside the bounds of recognized players that are already in the game are fraught with peril. If he tries it he'll end up with both the "heroes" and the "villains" teaming up to wipe him out. They don't like competition.

You should also point out to him that the reason nobody's decided to "become Batman" on their own is that the crime rate in the developed world is actually pretty darn low in most places (compared to the more turbulent parts of our history anyway), with the exceptions being primarily certain neighbourhoods in certain cities, all of which have a distinct lack of millionaires and billionaires who would be interested in his products. So if he really wants to succeed at this he's going to have to come up with ways to market his products for people on the poorer end of the scale as well.

One important thing to be considering, Mark: you should take care to document clearly, and with plenty of witnesses, that these are all his ideas and not yours. Otherwise you could be the one who gets arrested.

Or at least make sure to squirrel away some of the best tech for your own supervillain suit for when you get out of jail and take revenge.

Assuming he's in the US (and the courts are willing to uphold the 2nd Amendment), he doesn't get shut down. What are guns, pepper spray, tasers, body armor, &c but various technological superpowers?