A person who thinks he is the best–does that mean he has self-esteem? 900 years ago Rabbeinu Yona, a great Jewish leader, talmudist and ethicist said that haughtiness is a desperate attempt to escape feelings of worthlessness.

Self-esteem is based on a true awareness of one’s abilities. Low self-esteem means a lack of awareness of one’s abilities Simply feeling “I am a marvel and I am happy with myself” is not self-esteem.
— Twerski