The youth have an innate pressure to follow trends and their peers. They need and crave social acceptance while still lacking the means to be independent and “go their own way”, so it’s not viable to expect younger users to form the bulk of pioneering users of an unproven platform like the fediverse.
Older user will generally be more confident and independent, especially when the craving for social approval is not as powerful as it was in younger users.
I tell people it’s like signing up for a newsletter with your email, except the newsletter is also your social media feed.