Because arrogance, mightier than thou attitude, exclusiveness, thinking that somehow you are the only person in the world that ever achieved anything and worked hard for something, seeing the world in “us and them” setting, thinking that anyone who isn’t even slightly like you is undeserving of sympathy, having a belief that you are better because you had the luck to be in the rich, developed, fancy, secure, Hollywood style place and thus got a chance to be educated, healthy, and given access to every cool thing, unlike those filthy, illiterate, poor asses whose only sin is that they were born in some shithole in the middle of nowhere, or in some “lowest of the lowest class” in the society, and were never born under the same lucky star as you. Because of thinking that you are “the cool one” simply because you did the basic human function of not being a plant and doing something to achieve shit, and having enough luck to succeed.
Arrogance, looking from above and believing only certain people deserve to have nice things, while everyone else can fuck off, because they are not good enough.
That is what’s wrong with being an elitist. Because your head is stuck in your ass.