A bit depressing (and I hope no one is superstitious here). Are there artists you really wanted to see live, couldn't for a while, and then it was too late?
For me that would be Nirvana, Jeff Buckley and Rachid Taha.
For Jeff Buckley, it's even one of my greatest regrets, because I had a ticket for a concert a few months before he died, but didn't go because I had a cold. I can remember telling my mother there would be plenty other opportunities to see him live. What an idiot I was that day.