It's like scuba diving vs. snorkling.
I've been scuba certified for many years... till I realized that snorkling is 90% as fun, often better. But there is little money to be made off snorklers (just mask, fins, snorkle, about $50 total), and THOUSANDS to be made off scuba divers (BC, tanks, wetsuit, fins, computer, regulator, safety gear, weights, lights, boats, equipment bags, lessons, books, and on and on... about $1,500 to get started)
I tried a beach dive again last weekend. Hours of prep, renting my gear, carrying over 100 lbs of gear (2 tanks) around, poorly fitting wetsuit... it SUCKED so I gave up and snorkled. I saw MORE giant guitar fish, groups, stingrays, and other life than my pals who scuba'd nearby that day.
So lets compare: snorkling is about 1000x safer, 1000x cheaper, 1000x easier, and about 90% as enjoyable (being generous there). Actually snorkling is WAY more enjoyable... I can start and stop when I want (no decompression or dive tables), no need for a wetsuit so I'm way more comfy, and all my gear weighs less than 10lbs and can be carried in 1 hand. I don't need lights because there is no loss of color or light in the 30' of water where I hang out (and that's where most ocean life is).
So why do people scuba? It's HEAVILY MARKETED; the demand is CREATED.
Isn't this the story of modern life? People are like sheep, do what they're told, and they're told to buy into all kinds of crap that doesn't really make sense.