I suppose one might get the wrong idea about her philosophical premises from "The Virtue of Selfishness," where she identifies egoism -- enlightened self-interest -- to be the cornerstone of all morality, and "altruism" as the wellspring of all evil.
It ain't a side of her work -- it's the core.
It just isn't ALL of her work, which is what you are implying. And oversimplifying, too. Altruism is NOT the wellspring of all evil according to Rand, btw. More like forced altruism. I can hardly cover her whole body of work in a few paragraphs.