/ˈiːɡoʊɪst/
a person who thinks that he or she is better than other people and who thinks and talks too much about himself or herself

Your attitude to life is simple, direct, and aboveboard—every decision you make is based on the answer to one question: "What's in it for me?" If your selfishness, greed, and ruthless desire for self-advancement hurt other people, that's too bad. "This is a tough world, pal, dog eat dog and all that, and I, for one, am not going to be left behind!"

dog eat dog

when people compete against each other and will do anything to get what they want

ego 我
egoism n. 自我主义，利己主义
egoist n. 自我主义者，自私自利的人
egocentric adj. 自我中心的
nonego n. 非我
superego n. 超我M