Guys do still wear jockstraps. Many find them comfortable and enhance their athletics. If you want to wear one then do so. Don’t feel guilty, it’s just underwear.
I guess for a while guys got away from wearing jockstraps in favor of compression shorts. But I’m hearing they are making a comeback. I know at my HS most guys wear jocks instead of compression shorts. Definitely on sports teams almost everyone wears a jockstrap, or a jock with a cup depending on the sport. A pretty decent number of guys wear them for gym class too. Less than half, but maybe 1/4 to 1/3 depending on the class.
But I know its different even at other schools around here. I have friends at other schools who have never seen a jockstrap in the locker room. But they aren’t required to shower at their schools either – and they say no one does – and I think that makes the difference. If guys are so afraid of getting naked in front of each other that they would rather stink for the rest of the day, then they probably don’t want to change into a jock in front of each other either.