It is ALL-pervasive. Being a narcissist is close to being an alcoholic but MUCH more so.
Alcoholism is impulsive behaviour.
Narcissism is not a vocation. Narcissism can be compared to depression or to other disorders, but not to traits or attributes that we can change at will. One IS a narcissist. Narcissism is more akin to the colour of one's skin rather than to one's choice of subjects at the university. This is the seemingly eternal debate between the cognitive-behavioral theories of therapy and the psychodynamic ones.