Why do so many rappers need to put so much swearing and profanity in their music?

just because a person curses doesn't mean that they are uneducated or ignorant. jay-z, puffy and 50 cent all run various businesses and are very wealthy and intelligent people. This is like asking why heavy metal singers scream. It wasn't meant for everyone just as other forms of art and entertainment aren't for everyone. Just like jay-z says men lie, women lie but numbers don't. All 3 of these examples have went from humble beginings to being worth 100's of millions of dollars.