Dr. Ramani Durvasula discusses narcissism v narcissistic personality disorder: how to spot the difference on a video from medcircle. She says it's not a personality disorder when the narcisstic person doesn't experience distress. In other words, s/he may have narcisstic traits, but it is only a personality disorder when s/he is bothered by it because it is having a negative impact on his/her life. If the person is not in distress, then s/he is simply a narcissist (ie, the scientific word for jerk). I've always understood that one of the difficulties of having a personality disorder is that the disordered person doesn't recognize or realize that there is a problem. And, does it matter whether a person has a narcisstic personality disorder or is "simply" a narc?
These are great questions, sevenyears, and I wish I knew the answer. Hopefully someone else will chime in with some thoughts.