How is BJ a waste of talent? He's one of two guys (?) to hold titles in two weight classes in the UFC.
I agree with this. Even if he hasn't been at his best at all times, we've still seen what kind of force he can be when he is training to his full potential. So to say he has COMPLETELY wasted his talent is a bit far fetched. However, I would say that he is a much better fighter than his record shows.
As far as people who have thrown their careers away, a lot of good one have already been mentioned. Mark Kerr, Drew Fickett, Lee Murray...
I know he never went into MMA, but one guy that comes to mind for me is Kurt Angle. In a recent interveiew, he states that he was going to sign with the UFC, and fight at UFC 10, but they weren't able to negotiate the time frame that he wanted to train in. So they ultimately parted ways and he went into the WWF(WWE).(For those of you that consider Professional Wrestling a waste)
I think had he become a fighter, he would've potentially been a force to be reckoned with. He would've had arguably the best wrestling/wrestling credentials, could've developed a submission/grappling game and probably would've easily been a legend in the sport and a future Hall of famer. Plus, I think MMA would've been a better fit for him.