Just in terms of professional basketball players, I've heard Rip Hamilton doesn't drink, and has rarely (if ever) touched alcohol in fact. He mentioned something about it in an interview with SLAM earlier in the decade, saying something to the effect of simply "not wanting to get mixed up in that scene". But then again, Dennis Rodman is an admitted alcoholic, who has been to rehab for his problems with the booze (with some relapses), and has actually said that teammates would tell him that he "smelt like a brewery" when he arrived at some NBA practices. However, he is still an all-time great player without question, and one of my personal heroes for the way he's overcome adversity in his life. And ex-NBAer Keon Clark admitted he'd actually play drunk sometimes. So different professional players have different ways of going about thing, with varying results. Whether it is right or not is up to your own individual judgement obviously.
I'm not a professional athlete, but I don't drink alcohol. I go out and have a great time, just without ever drinking. If professional athletes want to do it, and they don't hurt anyone, infringe on anyone else's life etc., and it doesn't effect their performances (more their own and their coaches' concern than mine anyway), then they can go ahead and do what they like IMO.