Look, beef is a necessary component of rap music. Not EVERYONE could possibly be the best rapper, drive the best cars, have the best style, consort with the best women, etc, etc. Maybachs, G6s, Rolexes - all mass produced. Anyone can own one, provided they have the money.
Plus, for all the posturing, rappers are incredibly sensitive. Say one thing, even subliminally, about a rapper, or his crew, or his hometown, and BOOM - rap beef. So with all of the boasting, it's inevitable that rappers will butt heads from time to time. Here are some of the more... one-sided affairs.