Narcissism

Narcissism is a self-centered personality style characterized as having an excessive interest in one's physical appearance and an excessive pre-occupation with on one's own needs, often at the expense of others.[1][2]

Narcissus (1597–99) by Caravaggio; the man in love with his own reflection.

It is human nature to be selfish and boastful to a certain degree and there is a significant difference between being narcissist and self-absorbed and those having a mental illness or the pathology of Narcissistic personality disorder.[3]