It is altruism that has corrupted and perverted human benevolence by regarding the giver as an object of immolation, and the receiver as a helplessly miserable object of pity who holds a mortgage on the lives of others - a doctrine which is extremely offensive to both parties, leaving men no choice but the roles of sacrificial victim or moral cannibal...
Ayn Rand, The Objectivist, June 1966

Altruism is a code of ethics which hold the welfare of others as the standard of "good", and self-sacrifice as the only moral action. The unstated premise of the doctrine of altruism is that all relationships among men involve sacrifice. This leaves one with the false choice between maliciously exploiting the other person (forcing them to be sacrificed) or being "moral" and offering oneself up as the sacrificial victim. Why is the second considered good? Apparently because Jesus said so.

But the dichotomy of sacrifice or exploit is false. Between rational people, there should never be any sacrifice involved nor conflict of interest. The true moral interaction between two people should be an interaction as traders - trading value for value in a mutually agreed on and beneficial manner.

This is not to say that benevolence and good will are immoral. It is only sacrifice that is immoral, and being generally benevolent is not a sacrifice but a benefit and a virtue. The difference is that to be "good" according to Altruism, one must hand out blank checks to all who claim a need; while according to Egoism, ones own life is one's ultimate standard of value against which all acts must be analyzed.