I hate people who self-pity
What's so bad about self-pitying people?
I met a self-pitying person at a party and it annoyed me.
While you are allowed to dislike people with certain traits, you shouldn't outright hate them. You don't know their story as to why they always self-pity, even though it is bad to do so. They do bring others down by always being negative, but there's a reason.
You may be right but I don't care. I'm going to put them in their place.
You should just let them be. If they annoy you, just avoid them and leave the self pity.