was jon the bad guy?

His attitude is what drives the drama of the story.

However, you could see his effect on the band overall as being a net positive. He got Frank to take the mask off. Abandoning something like that WOULD make someone feel closer to a normal person in the long run even if they'd never be 100%.

He wasn't responsible for the original keyboard player hanging himself, unless you think that even helping pay for the band to try to record an album was somehow too much "pressure" for them to deal with.

The only real "villain" of the story is mental illness.

Not a bad guy per se, he was just wrong for the band and vice-versa. Plus, the band literally lived off him.

When you kill a man to defend an idea, you're not defending an idea. You're killing a man.

Nah, this band was broken before he entered it. He wanted fame and the rest did not.

He was the sane guy. And he helped them a lot despite all the hate he got from them. Hes an altruist, theyre lunatics.

my vote history:
http://www.imdb.com/user/ur13767631/ratings

Not one nor the other.

He was the normal likeable character at the begining of the film. He is the one that the espectator will most likely be identified with. The other characters are (very cartoonishly) portraided as freaks, outsiders.

The twist of the movie is that when fame strikes, the freaks remained true to themselves and "the normal guy" didn't.

So it's a nice way of putting "the normality" in perspective regarding art.

He was the bad guy, but I think he is also the victim of the social media logic, so he can't be trully blamed for his bad manners.