Why do ugly people look down on other ugly people?

while l was out l happen to see a short ugly bald middle aged man glaring at a passing lady who was larger and was having a bad hair day, however l can see she did the best she could to look decent although she did not have a naturally nice face, l dont know why the guy is looking disgusted with her when he is no looker himself, why do ugly people look down on other ugly people?