Funny, Slalom-Skateboarding is mostly older skateboarders as well - but that's partly because 1993 Jake Phelps took over Thrasher Magazine until his (fortunate for the rest of us) death around 2021. Phelps put the magazine into the dirt-bag red-zone by promoting underage smoking, drinking, buzzing, and Banning Slalom, "Real" Downhill (full face helmets, full body leathers, slide gloves, pack racing and good sportsmanship), longboards, pure flatland freestyle, and especially Banning ALL Helmets, Pads, Wrist-guards, etc. It was all to make money off of toxic-machismo badass-wannabe-ism and unfortunately trying to redirect that culture post-mortem of Phelps is indeed a hard thing to do. And as a result, most skateboarders now don't even know about Slalom or "Real" downhill, anything done on longboards, etc since the magazine still won't show it. I quit my subscription around 1995 when I saw where the magazine was taking things.
Also, the really good Slalom and Downhill equipment is soooo much better (the trucks are machined, not cast just to mention one aspect), it's priced itself out of most younger skater's budgets.
Then there's the world of Flying Model Aircraft -RC, Freeflight, powered, gliders, etc: It's mostly older members who make up the AMA membership (and very male, very white - I don't think that's due to racist or sexist exclusionary intent, it's just how it worked out) whereas Rocketry is much more age, sex and racially diverse which is refreshing to see.
Yes, I'm still racing at 61 (Grand Masters Division), I helped put on and raced (and raced well! especially for having plantar fasciatis in my Right foot) The World Championship of Skateboard Slalom practically in my own backyard this Sept/Oct 2023 in Salem Oregon and it was AWESOME!!!! 3 days of racing Tight, General and Giant slalom. And most of us putting it on are in the "older half" of the crowd.
That's my 4 centavos -PTH