Folding bikes are a technical niche so I'm seeing many of us have other hobbies.
I've always liked bicycles but only got into folders in 2009; first Dahon Curve, then Silvertip, then Mantis, then Dove, then Strida, and now Brompton.
This year I got an Argus Expert fatbike (sorry but it's the funnest bicycle ever) and am enjoying dirt since the early 1990s.
I'm on a folding bike break now, but the Brompton is a keeper though since it stores small and travels easily.
Every now and again I will build a diorama/scale model kit, or go snorkeling.

Other hobbies that have died off but I recommend for those interested in something new: autocross, snowboarding/skiing, 1/87 HO scale cars, Gundam model kits, paintball (2nd funnest hobby ever), pocketbike racing (funnest hobby ever), and radio control: 1/16 tanks, 1/10 drift, 1/10 crawlers, micro quadcopters (very cheap fun).
I played video games for 20 years but lost interest at the PS3: getting killed in Battlefield 3 online every 5 seconds took the fun out of it.
I only play games on my phone now because they are free.
As I got older: I realize it's best to not go in too deep because my hobbies only last 1-2 years before moving on.
Only bicycles will be a lifelong interest since you can ride into the golden years.