“Stop reading fanfic, you’re [any age over 25]!”
Uh. No. Just stop right there.
The adults over 25 built the fandom into which you wandered, once upon a time, enchanted by a story, blinking at the glare of possibilities beyond it.
One day you too may be 25—or 33, or 45, or 56, or 74—and realise you still want to be here.
One day you’ll get the first teenager yelling at you to stop doing fandom and leave it to the children.
If you can’t picture this, just give it a few years. Life may take you out of fandom or it may not, but the fact is, there’s no upper age limit.
You will pick up a job, a partner, a car loan. You’ll have children. You’ll take pets. You’ll lose that job, break up with that partner, go back to school, fall in love with someone new. Build a house. Break a leg. Bury someone you love. Life will happen.
But the things and stories you used to love will still be there. They’ll take on new forms. Trends and tropes and controversies will come and go.
On a purely personal observation—what else is this post?—fandom has been one of the constants in my life. I’ve drifted away and come back again, but the singular feeling of sharing a thing you love with other people has never gone away entirely. It’s a weird, messy, fractious entity, fandom is, but it’s always been a society that transcends generations.
You come into fandom thinking you and your peers invented it.
No, it’s always been here, and it will remain after you. In some form, held up by the people who came before and will come after you. That deserves a little respect.
(Now go read some Ursula K. Le Guin. She’s good for the soul, and better for perspective.)