I've been wondering what needs to happen to people in order for them to develop such a disgusting and hateful personality.
I think she was bullied herself as a teenager and now maybe feels like it's her job to return the deed or developed such a character as a protection so people won't get close to her.
Or maybe she just feels like she would be disregarded when she is being a decent human being and through the need of appreciation and attention she rather choses to act like this instead of treating others respectfully