Someone who is full of himself and doesn't give a darn about other people has a healthy supply of egoism. Egoism means "me me me me me-ism."
Egoism has a lot to do with selfishness, which sounds like a bad thing, right? Not necessarily. Some people think that being selfish is the best thing to do for the world as a whole. In other words, if everyone is selfish, everyone will be better off. So egoism can be considered positive or negative — it all depends how someone uses the word. This makes egoism different from egotism — an always yucky type of selfishness.