I think you answered your own question already. "Maybe its different in other countries, but I doubt it."Personal experience and common sense. The folks I encounter at pick-up hoops, like I said, all they need to participate in this hobby is a pair of sneakers - and alot of those sneaks are in bad shape. The folks I see hiking dont seem to be carrying expensive equipment either - I dont see alot of cameras or binoculars, just folks taking in the great outdoors. I wont bother to google it, but I'll assume there are way more hoopers & hikers than scuba divers out there.
If you want data, the median household income in the US was $67,000 in 2020. Most folks in the US are barely scraping by. Compare that to the demographic info CuzzA posted about OW students, who have more disposable income. I can tell you that when I was younger and poorer - comparable to the median US income - getting into scuba was cost prohibitive. Hoops, hiking and biking was more accessible. Only when I started making more $$ did scuba become more viable for me.
Maybe its different in other countries, but I doubt it.
Also, the AV income in the US needs a further breakdown.
From what I've seen, distribution is quite miscellaneous, for example, folks in Mississippi have almost half the income of those in Massachusetts. Also the middle class in the US is around 50% of the population while the upper-middle is around 10-12% and the high-class around 10%. In rough (non-official) numbers, out of 330.000.000 people, 66.000.000 (20%) should afford Scuba Diving...
As I previously wrote, my impression is that other factors like TIME are more relevant, especially the richer you become. Perhaps that's the irony, People with no money wish to dive while the ones that have it, are to absorbed making more
