Psychological egoism

Psychological egoism is the view that humans are always motivated by self-interest and selfishness, even in what seem to be acts of altruism. It claims that, when people choose to help others, they do so ultimately because of the personal benefits that they themselves expect to obtain, directly or indirectly, from doing so.

This is a descriptive rather than normative view, since it only makes claims about how things are, not how they "ought to be" according to some. It is, however, related to several other normative forms of egoism, such as ethical egoism and rational egoism.