As said earlier, it's so endemic in Hollywood that WB specifically put a clause in Cavill's contract banning him from doing so "because Superman doesn't do drugs".
Whether that was a "wink wink nudge nudge now our ass is covered" thing or not
Even actors like Damon are known to use them - I remember back before Jason Bourne came out some Hollywood trainers were talking about him (without using his name) and were like "Dude is in his 40s and had 6 weeks to gains 25 lbs of pure muscle and in return he got like $20M. Who wouldn't do whatever it took to meet that deadline, especially with how this isn't body builders shooting themselves with stuff from the streets, but the best medical care money can provide?"
