...These go to eleven.
That's nothing, I have played ones that go to twelve.
Anyway, yes, hearing damage and tinnitus can come from that, and it can be pretty bad. My father can't hear people speaking to him quietly, in part due to gigs, in part due to drumming, and in part due to being a contractor, loud power tools and machines. I lurk on a gun-related forum, and some of the older people there have bad enough tinnitus that they frequently can't hear normal conversation levels over the ringing in their ears, because they weren't wearing ear protection while they were young and invincible. I don't think there is any way to counter hearing damage, maybe listening to very quiet music, I know my hearing has gotten better since I have started listening to music at the lowest volume frequently.
I would say yeah, keep earplugs around, they only drop the volume by about 10 decibels (the good ones), but it will help, they might laugh at you, but you get to laugh at them when they can barely hear.