I agree with everyone else that you're never too old for fandom, but that maybe the way you interact with it changes. Or it doesn't, but fandom itself changes. Or both.

I'll admit that in the past few weeks/months I've been having similar fears, that I was just getting too old. But I think it's just that I joined a new fandom/pairing and it's a bit of a mess and I haven't found my niche yet.

My little corner of fandom before that (one I'm still in) turned out to be full of people my age, with similar attitudes towards drama/ship wars/nonsense. All very chill.

I'm generalizing of course, but younger people tend to be more intense when it comes to fandom? At least in my experience. It can be exhausting.