I have a friend who casually says "I hate white people." He is caucasian. Take one look at him and he looks white.
He is very vocal about his racial origins though, talking about how he is mostly a mix of Italian, Sicilian, and a bunch of other nationalities from that region.
So when he says "I hate white people" I think he is referring to anglo-saxon and germanic descended peoples. He doesn't like to think of himself as "white". But he is white, really.

I myself am mixed American caucasian and Lebanese. I consider myself white and an American. Yes I have olive undertones and generally darker skin shades then a lot of white people, and I'm hairier than a good amount of them too, but then again so are a lot of people.

I hear a lot of "I hate white people/men." I think it's something kids of the newer generations take to saying. I think for one, a lot of people in the newer generations are more mixed racially than any previous generations were, as the effects of globalization continue to transform the world. So these kids that are the product of many mixed races, even if they were brought up in America and born into the American culture, feel a need to differentiate themselves in take pride in their varied backgrounds, to stand out instead of being "just another American." "Yeah I was born and raised in America, but I'm actually French Canadian with some Brazilian thrown in." People so badly want to fit in and yet also so badly want to stand out, it's an interesting duality.

I think another big thing is that globally, from the perspective of races that aren't whites, the white race and more specifically white men are seen in a lot of parts of the world as the global oppressors of history. White men were the monarchs are the British Empire, white men hunted and enslaved blacks for centuries, white men gave rise to the Third Reich, the list goes on. The kids of the newer generations don't want to be associated with the stereotypical racist white bigot.

That's my opinion on the whole thing anyway, based on what I've seen/heard. I personally think a lot of people just care too much about race and not enough about individual character.