Iran hasn't actually done anything illegal in relation to the nuclear issue. As for help to Hezbollah, this is on a small scale compared to, for example, the backing which was given by the USA to the contras

It's a deeply flawed regime, but it's in power as a result of a democratic vote, carrying out the policies on which it was elected.

A lot of the responsibility for getting Ahmadinejad elected was down to Bush and his "Axis of Evil" talk and so forth. And, of course, to the fact that countries on either side of Iran had been invaded. Those are the kind of things that get extreme nationalists propelled to power.