Ego versus egoism; miserly and ignoble propensities; and megalomania
Everyone has an ego. It is not the ego that varies, but the qualities attached to it.
Yet people talk incessantly about this person’s ego and that other’s.
Ego, egoism (selfishness), and megalomania are three different things.
Megalomania, and holding oneself in high regard, not only do not entail, but by their very nature preclude selfish, miserly and ignoble propensities of any kind — which, in turn, do not imply megalomania or a high opinion of oneself. Bad people who are neither megalomaniacs nor possessed of a high opinion of themselves are by no means rare.
— A genuinely high opinion of oneself cannot be sustained if one displays qualities that contradict it, such as pettiness, selfishness, stinginess, or an unwillingness to part with what one has for the benefit of others.
Think of Don Quixote, Sherlock Holmes, or Beethoven. Beethoven in Copying Beethoven disparaging the model built by Diane Kruger’s engineer suitor, historical Beethoven disparaging Goethe for bowing to royalty — Beethoven explaining that his only reason not to commit suicide was that he had no right to deprive humanity of the priceless fruits of his genius.
(See: Taking oneself seriously, laughing at oneself, and the importance of what others think of us)