... Tony built the original Arc Reactor -- the one thing that makes the suit work -- as part of a government contract. Hell, the original armor prototype he threw together in the cave was built out of parts from missiles he created under another defense department contract. All of that research and development was done on the taxpayer's dime, and then Tony uses it to turn himself into a superhero and claims that nobody else has a right to put their filthy paws on it. In reality, it would be illegal for Tony to use an Arc Reactor to power his goddamn TiVo, let alone use it to fly halfway around the world and punch tanks in half (which incidentally is also illegal, because crossing national borders with that suit constitutes the trafficking of defense technology).
But knowing that he's in violation of federal law every minute he spends zipping around in his futuristic explosion suit only makes his other decisions that much more baffling.
We're not even including his facial hair and choosing to date Gwyneth Paltrow.
First of all, Tony openly admits to being Iron Man on national television. As far as the law is concerned, he might as well have announced that he had been smuggling weapons to Chinese pirates for the past seven years, because both are violations of the same set of regulations. Remember, there's a reason Bruce Wayne keeps his Batman hobby a secret: He knows that what he's doing is illegal as shit, billionaire or not. But Tony proudly confesses his criminal activities several times in the middle of a congressional hearing, then hacks into a few government computers (also a crime) and walks out of the courtroom flashing deuces. It's like he's daring the government to throw him in federal prison for a decade.
"Worked for Nixon."
After insisting that the Iron Man suit isn't a threat to national security as long as it remains in his carefully guarded hands, Tony proceeds to torpedo his own argument in Iron Man 2 by using the armor to drunkenly endanger people's lives at his birthday party and then fly, hungover, to eat doughnuts on top of another, larger doughnut.
"It doesn't count as a DUI if you have access to wrist lasers."