As a former musician in a punk rock/metal band and former frequent clubgoer, etc., I have had a lot of episodic problems with my hearing. Ringing, fullness, the whole nine yards. So now, even though I very luckily recovered each time from these symptoms (sometimes quite awhile later though) and without more hearing loss (so far), I have learned to be *extremely* careful with my hearing. I have several hundred dollars worth of various custom made earplugs for various environments and are never, ever, no matter where I go--without at least one pair.
We'll see how my hearing is in 30 years if I live to my 60s, but I've had serious life-threatning illness and major surgery and whatnot to deal with already, so I don't think that far ahead anymore. Today's a gift and that's it.
I write all that to say I feel I'm pretty knowledgeable about all this from my experiences and I think this whole hearing damage as a result of headphones is WAY overblown. You have so much more control with headphones than you do going out to a club there's no comparison. Same with any loudspeaker setup, car, home, or otherwise. Which is why I've pretty much gone to headphones exclusively.
Live music will kill your hearing a whole lot faster than headphones ever will--unless you're supremely stupid with your use. Ever go to a club and have the PA or a guitar amp freak out with feedback? Your hearing can be toast just that fast. Standing too close to the stage? Damage city. Have you been in a car crash with an airbag? You know how loud an airbag is? There are some that lost their hearing just like that from those. Ever had a balloon blow up next to your head? How about a gunshot? Ever ridden or been too close to a Harley Davidson? How about the air door release on a subway? What about a nice circular saw? It's ridiculous the rap headphones get while no one mentions any of this other stuff that are a MILLION times worse.
Headphones by comparison are safe and sane. Just give your ears frequent breaks. Taking the headphones off and walking around every 20 minutes is a great idea. Don't crank the music for too long. If you feel too much pressure turn the music down. And if you have to listen in loud environments, subway, etc., buy some IEMs so you're not cranking music up to cover background noise. You do have to fight the temptation I suppose to turn the music up loud (as you do in your car, or your home speaker system, etc.) But it's not really brain surgery.