Just came across this thread and thought I'd join in! I'm 25!
Also, can I just say how much I love seeing other people post that they've done solo trips in their 20s? I've done two solo trips of my own (one better than the other) and I've gotten some weird looks from people when they find out I'm there by myself. It's nice to hear about other people taking them!
I'm 28! I've got a Silver pass so I go often..ish. I love theme parks. I go solo all the time. I have even gone to SDCC solo lol. I'm not afraid to travel by myself if I really want to go somewhere.