Hating oneself or ones position in life often spills out into hating others and the associated negative behaviour comes out also. Seen it before, will see it again.
It must suck having to constantly prop oneself up in an attempt to find relevance internally and externally...Yet, never quite finding it...I've seen it before...The attempts become more and more desperate and while there may be some momentary feeling of well-being gained through tearing someone else down, when it's dark and quiet and the person is all alone, escaping the feeling of irrelevance is impossible to do by projecting negativity.