Why are some people so hateful?

I agree. Contemporary Whites should not be hated for something they weren’t involved with. However, note this; Blacks (and other races) still get hated for White racists’ misinformation, delusions, and beliefs that Whites are genetically superior to Blacks. Therefore, if SOME contemporary Whites carry neo-fascist and neo-Nazi beliefs, it shouldn’t be a surprise that SOME Blacks still believe Whites are evil for the past. Though I don't know for sure, I surmise the average Black person isn't anti-White and the average White person isn't anti-non-White. If that were case, racism would be apparent in nearly all facets.