I just looked up a demographics report on fishing, because in my mind fly fishing is analogous to trad archery, requiring a big investment of time and practice to develop technique and proficiency. I also expected a similar age spread that's being reported in this thread.
That report had about 44% of fly anglers at ages 45+ and 12% at 18 years old or less. Compared to 16% for other <=18 yo anglers (fresh and saltwater anglers). One interesting statistic was that the most common income bracket for fly anglers is $100k+.
Anyway, not trying to hijack the thread into fly angling, but I wonder if any of the archery trade organizations have any comparable stats. Not sure if there'd be a wider age gap in trad archery or not.
My feeling about "why" would be less time spent between parents and kids, passing down traditions (like trad or fly angling) on top of a general trend toward easier, quicker results, convenience, and general lack of attention span. Hours of form work, tuning, etc don't fit into the new cultural obsession with immediacy.
I'm 32 and mine the knowledge here a lot, posting minimally. I always appreciate that there *is* this group of archers who have the patience and resolve to pursue this downright worthy sport.