You are 14 and on Slate? It is odd to see someone from the age group which is usually on a less "intellectual" site like maybe MySpace or such, but this is intended as a compliment-really.
Anyway, before you call me an old geezer and ignore what I say, let me point out to you that rappers and rock stars (and professional athletes and hollywood movie stars) are not the people you need to observe if you want a role model unless you aspire to their jobs and have like talents. Drugs dont make you better at anything-they are called "recreational drugs" for a reason-not work drugs. I assure you that no artist and no athlete was ever made better with pot or any other recreational drug.
Now with that said, the list of drug using famous people can be greatly expanded if you include business leaders, scientists, historical figures, and many other less "celeb" celebrities. Sigmund Freud was high on cocaine for some of his best known writings, US founding father Tom Jefferson was toking ut up like Jerry Garcia and grew pot at Monticello, and Steve Jobs of Apple Computer fame bosted of his many LSD trips.
But these people were all who they were regardless of the drugs None would have been any more or less a genius with or without the drugs. But the health issues and damage the drugs could do if abused are undeniable. Freud quit cocaine because he saw he had become an abuser, Jobs isnt making millions by listening to the White Album-he is busy developing great products. And Tom, well lets just say that he had a tough life and no one can blame him (read his bio) for a little bit of chemically induced happiness.
So dont think drugs are any kind of answer. Drugs are a distraction-and not all distractions are bad in moderation. It is the irresponsible use (such as driving while intoxicated) or the abuse (daily use) which should concern anyone.