I think it's more about years in the game vs age unless you get on super late. If you get on at 18 and you got 6-7 albums out already you may be just 30-32 but that decade plus make you an OG/big homie to newer rappers (ie Nas, Wayne) but the same rapper who blows at 25+ will be in his late 30's with that same cycle. In recent history more rappers blow over 25.