From what I see (as a teen/ almost an adult/ technically an adult), is in high school, people are just busy, especially because standards are so high for HS kids now. You have to always be involved in 2 or more sports, or some kind of national society of something. But people either can’t get their minds past little Estes stuff, but once you show them the HPR stuff they say it’s cool, and I think the next step would be to bring them to a large launch or something. I've actually had some friends express that they want to go out to a launch, but since our local season is over it's much harder to do. And there are no large local areas that I could set up a small HPR launch (with proper paperwork)/ even if I could, I don't have the launch equipment.
So my advice would be, if it's your own child/grandchild bring them to a launch, and maybe try and fund it for them a little bit so they can move and afford to fly the larger stuff, because that what people think is cool, and it will keep them engaged. And of you have a local club, spread the word around your neighborhood or something, leave your biggest rocket outside, leave a flyer for the launch. I dont really know, just thinking out loud.