Dr. Evilstein doesn't want to market his technology himself because most businesses fail within their first year of operation, and doesn't want to have to answer to employers or investors he considers to be Pointy Haired Bosses.
Dr. Evilstien knows that his invention is too evil and he couldn't sell it legitimately.
if everyone and their brother had access to Dr Evilstein's tech, he wouldn't have the edge.
Dr. Evilstein is really just the Disc One Final Boss, and someone else more powerful is controlling/blackmailing him into using his inventions for villainy.
Dr. Evilstein tried to sell his devices to investors, but they all rejected him either because they thought It Will Never Catch On or because the device was dangerous and brought the risk of lawsuits. Infuriated at being rejected, Dr. Evilstein decides to use his inventions for crime...starting with the people who rejected him.
Dr. Evilstein's logical and mathematical abilities allow him to fill his own special niche in the criminal underworld, whereas using his abilities legally would just leave him one among millions in academia.
Alex has terrifying powers that could easily make him incredibly wealthy. However he is too moral to abuse them in that way, instead he uses them for mundane tasks like extermination of vermin which gets him far less money.
Bigg Banga, a rapper with explosive eye beams, has an album that's about to drop, so he blows up a parked car to get a few cameras pointed at him.
Dr. Evilstein makes far more money (and / or respect, power etc.) out of crime than he would legitimately.
Discussed: "Couldn't this guy just make more money than banks ever have by going legit?" "Completely correct, but this isDoctor Evilstein we're talking about".
Conversed: "Have you seen the technologies those villains have? Why won't anyone cut Lex Luthor a check?" "Well, if all villains suddenly went legit there wouldn't be much of a story, right?"
Dr. Evilstein got his start in criminality because he got screwed over by a Corrupt Corporate Executive who stole the intellectual property rights to his inventions. The bank robberies are in fact an elaborate plot to screw this very executive right back.
Dr. Evilstein is an Corrupt Corporate Executive who design his inventions so they would be as expensive as usefull, so only weathiest can afford them and he can ear insane amounts of money.
Dr. Evilstein tried to market his inventions legally, but his business failed. Now he tries to earn money from his inventions the only way he can think of.
Dr. Evilstein tries to move into legitimate territory, but his villainous impulses keep getting the better of him and jeapordising that goal.
Reconstructed: Dr. Evilstein gets the rights back, but continues to rob banks because he's grown to like it, and is wanted by the law.