It’s more than just vanity (excessive pride in or admiration of one’s own appearance or achievements); we’re actually wired to find it pleasurable.

Harvard neuroscientists Jason Mitchell and Diana Tamir found that disclosing information about the self is intrinsically rewarding.

In one study, Mitchell and Tamir hooked subjects up to brain scanners and asked them to share either their own opinions and attitudes (“I like snowboarding”) or the opinions and attitudes of another person (“He likes puppies”). They found that sharing personal opinions activated the same brain circuits that respond to rewards like food and money.

-Contagious, p.33