To answer your question regarding the lack of younger people (20s-40s); poor marketing aside - it has to do with time. Most of my peers are mired in jobs working in excess of 50 hours weekly. After work, those with spouses and/or children simply don't have the time to do much of anything. I was fortunate in that I had flight park 40 minutes from my home, my then girlfriend - now wife, knew that hang gliding came with the package. Not so for others. The work / life balance is a hard walk in the 21st century and most simply can't commit the time to learn, let alone fly regularly enough to maintain currency.
I know this is an older thread but I wanted to add something to it. I am 17 y.o., an H3, and I love this sport more than life itself. I know that on the whole my generation is not that impressive, most of my peers like to play video games and sit inside while I run around doing stupid things like falling off trees in the woods. This being said, I don't think it is a generational thing that makes us a less motivated group.
I was brought into the sport by my father, a H4 and a super pilot. He also teaches regular aviation. I grew up flying with him and my grandfather, who owns a Bonanza, and watching him hang glide, until one day I said, "Screw it. I wanna do this." I spent nearly 4 years on the training hill with literally hundreds of flights because nobody wanted to sign off on the kid going off the mountain, which I understand (doesn't mean I or my father were happy about it). Finally, after training with many different instructors (which was, in hindsight, a great opportunity because I gained exposure to many different flying styles and techniques and added to the knowledge I already had from drilling my father with questions in the car whenever we drove anywhere), I got to launch off the mountain. Since then I have put in a lot of time flying and did a lot of aerotowing as well.
I guess what I am trying to say here is twofold, the first being that I agree with many of you, people will only stick to what they are devoted to accomplishing, but to disagree with you that the reason younger people aren't getting involved is because we are a weaker or less motivated generation. Many of my friends are going to try hang gliding this summer, but only because I took the time to explain to them what hang gliding was in an interesting way.
Also, in all of my very short 17 years of experience, I have not met many people who knew what hang gliding was. Most said, "its the thing like the parachute right?" The advertising for the sport of hang gliding is going to be crucial to its expansion and development, and the core of the advertising is each and every one of us.
As a young person, I will note that there is, on most websites regarding hang gliding (not all), a very obvious lack of effort. There is also very little presence on social media. One of the few manufacturers who consistently posts new pictures and news is WillsWIng.
In response to the quote at the top: I am in boarding school and I found a way to continue flying. I can only imagine how hard it would be to find time especially with a family, but maybe bringing them along is a great way to get more people interested in the sport. It worked like that for me!
In conclusion, I must reiterate how much I love this sport. It has been both the cause of frustration in parts of my life, and the sweet release from stress in others. I think that to get younger people involved in the sport, we need to make it more accessible to them through technology and advertising. We need to reawaken the dream of flight in people. And the best advertising comes from a hang glider pilot who can talk about the sport in a way that makes sense to those who haven't participated and with a vigor which captivates.
That's my piece. I recognize that I am only 17, but I feel that all people have wisdom to share and it would be worth hearing a younger perspective.