Students for the Exploration and Development of Space (SEDS) has a fairly active chapter at my Alma mater UCF (graduated 2015). Unfortunately, the younger crowd (<25, myself included) of rocketeers will always be small comparatively due to costs associated with the hobby. After getting my L1 through my employer, I struggled to justify motors larger than 29mm since reloads bordered ~$20 per, and that's a lot of meals for a Senior in college/fresh grad. Compound that with studies, limited transportation ,etc. it was hard for me to get "into" the hobby through launches. Building is what I spent most of my time doing and now I have more rockets than I have launches (soon to be fixed).
I think many of the younger guys in Scouts/school get that initial spark as I did, but pursue the interest in whatever way they can within financial and educational limitations. With new tech becoming more prevalent in daily life, I think we as hobbyists should focus on the software-->design-->build aspect of rocketry for the younger groups. OpenRocket is great for technical data, but isn't much fun for young kids to just get creative. I'd suggest a more drag-and-drop type rocket software where kids can "build" a rocket to look cool (pant schemes, fin shapes, etc.) and then the parent/teacher/NAR instructor can help them build it. Or a company could do quick custom work based on the images and ship the kit to the kids to assemble. I know Estes has some of the DIY kits with lots of supplies, but those can be daunting to work with if you just want to have fun designing.
As I get further into this hobby I am meeting all sorts of people that are really into the different aspects of rocketry; with some liking motor development/testing and the chemistry, others liking the programming/electronics, and many just enjoying the build. I think you're going to see more SEDS students and college age rocketeers start to pop up as they find the thing that interests them within the hobby, and especially as the commercial "Space Race 2.0" heats up.
TL;DR: It's expensive for younger guys to move up quickly. But college teams and engineering programs are helping. Get involved with SEDS chapters or start a new one if your college/university doesn't have one! Also, please send money for rocket motors! Thanks mom!