I've been around diving a long time, and even now, I have several friends that own dive shops. I'm also in Canada, which is a relatively small diving market at the best of times. This topic frequently comes up when we talk about the challenges facing their businesses...
I think there are a number of reasons:
* initial cost is high as stated, and with the still-sluggish economy, that age demographic is "under-employed" to some extent
* those that are "well-employed" are saddled with student debt
* there is more competition for "adrenaline sports" - jet skis, kite-surfing etc. (ya, I know rec diving ain't exactly adrenaline-inducing, but non-divers don't get that...)
* many in that age group are video babies. They would rather sit inside and play video games
* diving isn't perceived as a socil sport, and that age group often does stuff in "gangs". Dive clubs tend to be filled with fat old people (like me... although I'm not really in a club).
Having said all of that, we have a group up here... Great Lakes Technical Divers (
Great Lakes Technical Divers)... that has a bunch of younger folks in it, that are keen, investing in gear and training and who dive constantly. They're all off to dive Bell Island in Newfoundland this week to dive "Truk North"...
For what it's worth, it's my understanding that many activities have the same problem of attracting younger folks... golf, skiing etc.