It is common knowledge among psychologists that most of us underrate ourselves, short-change ourselves, sell ourselves short. Actually, there is no such thing as a superiority complex. People who seem to have one are actually suffering from feelings of inferiority; their "superior" self is a fiction, a coverup, to hide from themselves and others their deep-down feelings of inferiority and insecurity.
Maxwell Maltz, The New Psycho-Cybernetics: The Original Science of Self-Improvement and Success That Has Changed the Lives of 30 Million People
arrogance, confidence, ego, insecurity