The biggest obstacle is their own character. If they are obsessive, manic, hyper, intemperate or psycho/sociopathic as they often are, then they will fall victim to all the obstacles listed on the poll.
It comes down to the era, really. In the 1980s it was drugs. In the 1990s/2000s it's been politics (to an extreme degree). In the early days (say pre 1960) it was difficult to get promoted correctly. Alot of excellent fighters simply wasted away because they fought too often and got burned out, even though most of the time it was for little to no money OR publicity. The biggest one I can think of, even if it isn't really relevant today, is racism. A HUGE factor in matchmaking and title politics through the 1940s, and it remained a factor until probably the Clay era. The early guys had it worst - Johnson and his predecessors. Wills comes to mind as a post-Johnson guy who had trouble, Moore too.
This is probably the answer that I most agree with. A fighter chooses his own fate, but a lot of times his upringing plays a role as well.
It's politics/management/promoters/the busineess side. That's ALWAYS been the biggest obstacle, because it can affect any fighter, and tends to effect them all to some extent. A fighter can choose whether he wants to fall victim to those other things, but management and promotion can mess a fighter up from day one. And every manager has to play the game to get his fighter opportunities, in a cut-throat business, and often ends up looking out for himself against his fighter. Bad management and lack of promotional opportunities (and the right connections) can be the difference between a fighter becoming a great champion or becoming second-rate cannon fodder. That's the brutal truth of it.
I agree that Promotional politics of boxing / contracts if the #1 obtacle for great fighters. The sport politcs of boixng hurts the sport more so than any other sport I can think of. How sad.
It depends a bit on the situation the fighter is in. If someone is champ already, then drugs, money, fame and the feeling of invincibility is the most dangerous thing by far. See Frazier, Foreman, Bowe, Tyson, Liston etc. If it's not a champion, then promotion etc. Especially if you were black and a contender pre-30's.
