I think there's a lot of truth to that. I've met quite a few successful comedians and many of them do seem to have sizeable chips on their shoulders.
Given that successful comics harbor more rage than most, what about the ones who try comedy but fail at that? They must be even angrier!
Here's a story from Renton in Washington that certainly feeds that stereotype:
Dylan Avila was hosting the weekly open mic comedy night at Local 907 when he was attacked.
Witnesses said Steven Baldwin rushed on stage and began striking Avila with an aluminum bat.
"He was one more hit away from killing me," Avila said.
Avila's friend, James Taylor, and several others jumped in to save him. They fought off Baldwin and held him down until police arrived.
The man wielding the bat was actually a wannabe comic who had performed at previous open mic nights at the venue. But because his act was so inappropriate, Avila banned him from the stage. That's what set him off. Given his reaction, you get an idea about what his act might have been like!
Even though Avila's skull was fractured in the attack, he managed to return only weeks afterward. This would have been remarkable in any profession. But in the field of standup comedy, it seems doubly so. Being such a physically and psychologically resilient bloke, I suspect Avila is the exception that proves the rule!