I do. Before when I first started, I didn't because I thought there were no strikes so I'd be fine. A couple of months in, a wrestler dropped by for a free trial. We rolled, and I pulled guard. I was shitty at take downs then, and no way was I going to take a competitive wrestler down.
Anyways, I pulled guard, and of course, he didn't want to get in my guard and resisted and tired to make it a makeshift pass. He ended up in half guard, but on the way down from standing to half, his knee came crashing down onto my junk.
I've worn a cup since then, I don't give a shit if some guy drinking the kool-aid says not to wear one, because in comps. they ban it, and it'd be best to keep it "realistic". I'm not in the business of ruining my evening / weekend because of that. Also, shorter guys shooting takedowns on the fence/wall, ends up with their shoulder bumping into jr, so there's another reason I wear my gear.
The only gear I don't wear is an ear guard, I haven't found the need for it. No signs of cauliflower forming so far.
I'm just using a basic jock. A teammate of mine swears by thai style steel cups