You are well below the age of the average person to go to (I assume musical act) shows as well as being below the average age of any bar I've ever been to. Perhaps you are picking venues and acts frequented by college students or are overly self-conscious?
It's very weird to be basically at peak age and to not go to events because you're the oldest one there. Were you exclusively going to high school band shows and 18+ events?
In retrospect I think I was hyper focused on a couple of pre pandemic examples that stood out to me. Thinking about it a little more it depends on the genre. I’ve definitely been to some shows that have different demographics.
Sounds like you might be going to the wrong bars/places? I'm late 20s and already married but have friends who are single around my age. My local places are late 30s - 50s with a few people around my age but if my friends want to meet girls I take them to different places where they tend to be a younger crowd (early - mid 20s). If you don't want to drink, you could check out gym classes too - some have decent social circles built around them.
More than that I’m wondering if I’m just living in the wrong places. The place I live right now is generally more associated with retirees, but I’ve never really made a conscious choice to move somewhere. I’ve just drifted where job offers take me.