I was 16 when I bought my first bike. At 18 I did all of the planning for a buddy and I to ride our bikes to the Black Hills for 3 days. That bike taught me responsibility, independence, how to take care of myself. This was in 2007 so not ages ago.
Only you know your kid, but this can be a great thing for him or can be a financial burden or worse. Give him room to take responsibility himself but keep some guardrail up so he can’t get himself into trouble.