Because the universe spoiled him with a natal Jupiter/Sun conjunction in Gemini (ruled by Mercury). He's always really had it easy even when he didn't. Add to that a Pisces (delusional) Moon and his Moon being his apex (focal) planet which makes it overly sensitive, and you've got someone who thinks they know it all. Kanye said what he did because he's smarter than the rest of us. He knows what's what.
But here's the 411. Kanye just got a progressed Mars square (bad) to his Mercury (communications). So play with the universe and the universe slaps back. In addition, his progressed Mars is sitting on top of his natal Mercury. So slander and libel could become his best friends if he doesn't put a sock in it.