In the introduction to her collection of essays on ethical philosophy, The Virtue of Selfishness (VOS), Ayn Rand writes that the "exact meaning" of selfishness is "concern with one's own interests"
She rejects altruism, the view that self-sacrifice is the moral ideal. She argues that the ultimate moral value, for each human individual, is his or her own well-being. Since selfishness (as she understands it) is serious, rational, principled concern with one's own well-being, it turns out to be a prerequisite for the attainment of the ultimate moral value. For this reason, Rand believes that selfishness is a virtue.
This goes beyond put the mask on yourself first before you help others....Altruism permits no concept of a self-respecting, self-supporting man—a man who supports his own life by his own effort and neither sacrifices himself nor others…it permits no concept of benevolent co-existence among men…it permits no concept of justice" The truly selfish person is a self-respecting, self-supporting human being who neither sacrifices others to himself nor sacrifices himself to others. Read this analysis
And consider the book