I believe that many professional athletes have underlying psychological issues and that their achievements are part of the coping strategy (how many of us use sports to cope with depression, stress, feelings of inadequacy? hell, I do).

So a lot of them probably are susceptible to the temptations of drugs.

In addition, they get to go to parties where the stuff is around, and they easily meet the kind of people who use it (well doh, it's everywhere where people "work and play hard").

Yes, he's an idiot and if he does not find a way, he'll fall.