I used to play in bands and go to concerts without earplugs too, and one of my favorite pastimes is listening to music on loud volumes. Yet I've never developed tinnitus.

I guess I'm just lucky, or my hearing is just so sensitive that what I consider "loud" is actually fairly quiet. I know that I've had problems actually hearing sounds in band practice without using earplugs - I'd just hear a bunch of noise, and often lose the beat because of the inability to hear other musicians clearly.