you cant act "gangsta" for the rest of your life...eventually you have a wife, kids, family and those things become the most important parts of your life. i think that is why alot of them are using rap as a platform to bigger things like fashion, acting, and other business ventures. rappers like P. Diddy and Dr. Dre dont really rap much any more, they make their money making beats, selling clothes etc. if you havent built some type of platform to keep you in the limelight, you will just fade away.
If young people are better rappers than older people, I guess it's not the kind of art form that you get better at with experience? I mean, most jazz musicians start to find their voice around age 30 and hit their prime at 40. If rappers hit their prime at age 20, what does it say about the music? That it's more important to be young and cool than to be good at the craft? The reason I compared it to jazz, is because I suspect that in actuallity rappers should be getting better with age. They should be refining their control of rhythm, building their vocabulary, and starting to talk about real subjects. A 40 year old rapper should be able to give us more insightful lyrics with a more polished delivery, assuming they kept practicing and experiencing life throughout their 20's and 30's.