Although the saying goes, "nice guys finish last," being a total jerk doesn't get you to first either. And these celebs prove it. Source
You may remember Michael Richards, who played Kramer in the hit comedy series, Seinfeld. In 2006, he made a racist comment while doing his standup comedy routine. The scandal become widely known at the time and his career seems to have been ruined because of it. He's managed to get a few projects since and he has publicly expressed regret for his ill thought out actions, but I don't think his career will ever recover from it.