Vigilantism is never a good idea.
All you're doing is imposing your idea of morality on the immediate society and break the laws at that. Who the fuck are you to say what's right and what's not?
A serial killer who truly believes that California will drown if he won't kill X people is AS correct as some vigilante similar to Punisher. Why? They're both following their personal beliefs, and they're both zealots in that sense. Except one happens in real life, and another is an idealized comic bullshit.
At least when the government does badly, we can all grumble and protest at it. If just random people started doing what they thought was right - it'd be anarchy, no less, and while I do support the idea of unrestricted anarchy - that will NOT do good for society. It'll be fun for as long as you can survive, but afterward all you'll have is wreckage. Some kind of society, with a set of rules, is necessary if you're interested in progress of any kind. Of course, if you aren't - go for it.