One of the teachings of economics is that humans are, generally, self-interested. Critics of economics have seized upon this terminology to argue that economics (and free markets in general) are promoting selfishness. It’s the whole “greed is good” mentality. Nothing could be further from the truth as there is a distinct separation between selfishness and self-interest.
Selfishness is marked by a lack of consideration for others; the self is supreme.
Self-interest is looking for the best ways to promote’s one welfare, how to make one happy. This includes caring for others.
I have a family whom I love. I have friends whom I love. To the extent I can, I try to be generous with them: buy presents, spend time, that sort of thing. This is self-interested behavior perfectly consistent with economic theory. Taking care of my family and friends makes me happy, plus provides a safety blanket. It also fills social needs and desires.
This is just one example of self-interest, but there are many more: charity, friendship, neighborly love (perhaps, one might say, the Christian Virtues).
So many of the moral criticisms of economics and markets stem from confusion over these two terms. Perhaps I shall write more on this topic in the future.