egoism / egotism
Self-interest as a doctrine versus conceit.
Egotism is the common word for talking about oneself, or for conceit. Egoism is the doctrine that self-interest is the ground of action. If you mean conceit, use egotism.
Examples
Useplain egotism
Useethical egoism
Avoidethical egotism (If you mean the doctrine.)