Wasn't alive in the 60s and don't have a US perspective only a UK/EU one. My parents did see the Stones in the day and I distinctly remember them struggling to decide whether they should go see them in the 00s because tickets were 100€+ (seems cheap now!). But they are not "super-fans" I guess.

I also remember festivals getting more expensive 15-ish years ago, so my friends and me often decided to go hiking instead. IDK if that's a typical case but there are alternative "experiences". With the rise of social media I could understand there's additional incentive to go to more well-known events for the photos, over smaller live-music venues. At least it seems like a lot of photos are taken.

This is all anecdotes, so makes for an unsatisfying answer. But I think it's possible (certain) "experiences are more valuable to generations today". It's at least interesting to consider.