Some people do, most of them don't. Look, to me the tweet above me suggests this was basically his agent/NHLPA telling him to go to this program, if you admit you have a serious problem maybe that isn't a valid reason to terminate your contract. I'm not a CBA expert, but I've kinda got the understanding that the teams can't just terminate a contract if there is substance abuse, but need to relay the player to the assistance program.
And I'm not saying that Galchenyuk is only doing this because of his hockey career, I just think the idea was sold to him based on this. Maybe the two things are unrelated and he really sought help himself. If so, good on him.