"A competent and self-confident person is incapable of jealousy in anything. Jealousy is invariably a symptom of neurotic insecurity"

This quote by Robert A. Heinlein suggests that a person who is skilled and self-confident is not vulnerable to jealousy. Jealousy suggests insecurity and a lack of self-confidence. It suggests a person's inability to trust themselves and their own capabilities. A competent and self-confident individual is safe in their own capabilities and does not feel the requirement to compare themselves to others. They are safe in their own worth and do not feel threatened by the success of others. They are able to celebrate the successes of others without feeling threatened or envious. They have the ability to trust themselves and their own abilities, and do not feel the need to be envious of others.