who is a well known ethical egoist
The philosophy of ethical egoism states that morality should be based on self-interest. Ayn Rand is a well known example. She came from a privileged background and had little sympathy for the underprivileged.
Henry Sidgwick conceived of egoism as an ethical theory parallel to utilitarianism: the utilitarian holds that one should maximize the good of all beings in the universe; the egoist holds instead that the good one is ultimately to aim at is only one's own.