Just turning 25 here in a week or so and i only discovered game jams within the last 6 months or so. I've been pretty obsessed since then and have had a ton of fun making games.
I do feel a bit old in some of these jams but these jams are mostly just for the fun and experience.
I've learned a ton and have gotten a lot of good feedback that I think has helped me improve as a programmer and game designer.