Wonderful question! Uncertainty; most important part in our life. You never know what's going to happen to you, and what happens to you, may never happen to another and it usually doesn't! It's a miracle how a 65 year old person could have a very complicated heart surgery done, and live for an extra 20 years with no problems whatsoever, and a 20 year old person who merely got a teeth pulled out gets the tinnitus and has to suffer throughout his life. Same goes with everything in life. There's always pain & gain for different people. You can put two people under same conditions, and yet see varied results. It's the effect of our lifestyle.
When we talk about noise induced tinnitus, it's a common misconception IMO that people think they got it
ONLY because of a one time gig. Some cases, yes, it might be due to a one time clubbing where the music was too loud and it damaged the ears and caused tinnitus. But usually, I don't think that's the case. I've seen so many people who frequently go to clubs, who work at construction sites constantly exposed to loud sounds, etc. Many don't have tinnitus or hearing loss. Of course, they will have some problems in the future. But in your case, you mention you got tinnitus due to a concert. Yes, that could be the reason. Alternatively, you may be unaware that you had been exposed to loud sounds when you were a kid. Looking back at all the years, I now feel that there were too many reasons my ears could have been damaged(my ears don't have any damage right now, I'm just saying that many situations existed). People bursting firecrackers, friends at school shouting in the ears as a prank, the teacher yelling standing right next to me, truck horn being honked when I was next to it, etc. While these come off as normal scenarios, these often do cause problems. We may not notice anything significant, but all these add up and cause problems.
Just a few days ago, I saw a man hold his daughter, probably a year old, and was talking to her sweetly. He then starts snapping his fingers and she starts laughing. He continues doing that and he starts snapping near her ears. He then starts making some weird squeaking sound to make her happy. He's holding her up and making that sound right next to her ears! That's when I realized not everything in your hands. That poor kid could have hearing problems right then! When she grows up, she'll never know what happened. She'll be told she was born that way and there was a problem with her hearing since birth.
And finally, hereditary. Lots of problems are hereditary. You're born that way, there's just nothing you can do about it. It depends on your luck I guess. I've seen people with so many problems and others with absolutely no problem. It's really bad when we compare those two extremes. But anyway, I've also observed that if one lives a comfortable life initially, life always gets you in the end. One either starts living with small problems throughout their life, or they enjoy their life first, and get something big in the end. Some exceptions do exist.
Like you, I wonder how people have their iPods at high volume and yet manage without any problems. But I tell ya, they're gonna get it someday soon. Right now it's all fine. In future, there's gonna be some or the other problem associated with it. It's just the way it is, you've got nothing that can be done. Everything has it's ups and downs. Me, I just can't lay off of McDonald's delicious burgers. I've reduced a lot though, I visit McDonqle'w once in 2 months only. But I know very well that it's gonna affect me in future.
Summing up everything, I mean to say that everyone gets some or the other problem in life. Those who don't, are extremely lucky! To each, their problem is usually the worst according to them. Us tinnitus sufferers sometimes think that having some other disease or disorder is better than living with a noise all the time. And people with those diseases think it's better to live with a sound than with a disease all day. One knows how it is only when they experience it. Life sure is weird!