If you have ever listened to a rap song, you will notice a common theme: pleasure. Pleasure drives people in general, but what is it about gaining clout and fame that makes all these rappers so similar? Basically, all mainstream rappers value the same things such as sex, money, and drugs. They value sex because it feels good, money because spending it feels good and drugs because it feels good.

Your basic, not famous civilian might value these things too, but on a much lower level. They do not have the right to brag about how many women they have or how much money they make at a show because average, nonfamous people don't have those things. Yeah, people do tend to like money (it pays the bills) but why does being a rapper put those things on steroids?

“[people] with no money act like money isn't everything” -Drake

Then there’s drugs. Most people who have done drugs did them as a teen to experiment. If that is not the case, that means they are actually addicted to the substances and everyone can agree, that being addicted to a drug is not what makes them “cool”. When people do take drugs, you don't see them bragging about it either, it's usually done on the down low. But, It seems that if you're a rapper, bragging about your intake is part of the experience.
Once you get lots of money, have lots of people who are willing to do sexual things with you, and have access to all the drugs in the world without being judged, the pleasure becomes addictive.

“I was sober for an hour but I'm rollin' off a bean now
The drugs, they give me confidence, I'm sayin' what I mean now” -Nav

I think that fame in general can really tell you a lot about someone. Famous people can basically do whatever they want, and still have fans. Take Britanny Spears for example, she shaved her head and beat paparazzi with an umbrella. Today she is considered a mogul and people look up to her. If fame had not been on her side, she would be a social outcast. Since you can get away with doing basically anything, as a weak human being you are drawn to drugs, sex, and the greed of money.

“I got the juice like that, I could get away with murder” -IamSU