The younger riders live to ride.
Most young adults are trying to establish relationships, a career and pay thier bills.
Only a fortunate / passionate few are able to continue to "live to ride".
We are seeing more athletes competing at elite levels into thier forties. I started riding at 46 (my kids thought I was too old)l I have aquired enough skills to race now and I chase the kids. Its very bonding & keeps me young.