Well, I think it's a lot more common than we stupid psychology professionals think ... well, I say "stupid" but the truth is that NPDs seldom seek treatment, and they have reality all twisted into a pretzel for their poor children and other victims, so those people even when they are suicidally depressed don't often realize that it is their sicko NPD relationship that is killing them. So they don't report it every time either.
Another thing ... I went to a conference this week and they were talking about "Axis II" disorders. For those of you who haven't done psychology (I know there are a lot of you who have, though), Axis II refers to both personality disorders and MR ... stuff that isn't likely to go away and is a foundational part of who the person IS. Right now we have a "categorical" system --- so that a professional will tally up a person's symptoms and if he/she has the required number of symptoms, then a diagnosis is made. That may work fairly well for depression, anxiety, other things that come and go, but with personality disorders, it doesn't work so well. It is uncommon for somebody to just have ONE Axis II diagnosis. Plus, it has been noted that the most common Axis II diagnosis for women is borderline PD, and the most common for men is antisocial PD, but those two are thought to be the divergent ways men and women respond to chronic stress/trauma. They are not that really different. Both are loosely described as narcissistic disorders, although they are not called NPD. Right now, the American Psychiatric Association is going through an extensive process of revising the way we categorize mental illnesses/disorders, and the whole personality disorder category is being reconsidered. THe bottom line is that our way of identifying and categorizing the lasting, unresponsive, dysfunctional personalities is still pretty crude and primitive.
You can just barely have the required number of symptoms and be diagnosed with a personality disorder, but the severity of those symptoms can vary widely. One person who is diagnosable as NPD might function pretty darn well except for times of stress. Another person may not quite make the necessary number of symptoms, but the symptoms he or she DOES have are really bad, all the time.
So, I personally recommend taking what you read about base rates of NPD with a grain of salt. We really don't know enough to draw really good conclusions about these things.
I'm glad you all are able to laugh ... I know sometimes it feels like gallows humor but your very ability to see the absurdity of all these situations is in my opinion evidence of your healthiness. Keep on laughing (just not in your NPDs face unless you want to see them catch fire and implode ...)