Narcissistic personality disorder (NPD)

A psych-major friend of mine felt the need to share with me her primary diagnosis for "my case" :
She felt that I show almost every symptom of Narcissistic personality disorder : she gave me a 8 /9 on the diagnostic criteria for NPD :

Diagnostic criteria for NPD :
At least five of the following are necessary for a diagnosis (as with many DSM diagnoses, they must form a pervasive pattern; for example, a person who shows these criteria only in one or two relationships or situations would not properly be diagnosed with NPD):

1. has a grandiose sense of self-importance
2. is preoccupied with fantasies of unlimited success, power, brilliance, beauty, or ideal love
3. believes that he or she is "special" and unique and can only be understood by other special people
4. requires excessive admiration
5. strong sense of entitlement
6. takes advantage of others to achieve his or her own ends
7. lacks empathy
8. is often envious or believes others are envious of him or her
9. arrogant behavior

more about NPD : here

And I couldn't help but laugh when she told me about it ; I've been reading some psych-related articles or in some cases books and I found the field fascinating to say the least. It's amazing how the whole science is revolving around finding what makes people different from a prototype and then deem that difference with a "disorder" . It feels like the whole thing was created and documented by boring middle aged women who decided to judge everybody , and fit them under a category !

I mean could that difference mean that the people are DIFFERENT plain and simple ! Doesn't attention Deficit Disorder mean that the person could be merely athletic and can't concentrate on "wordy stuff" ? And doesn't bereavement disorder mean that the person is actually SAD !? Doesn't Body Dismorphic Disorder mean that that person is "a blond" ? etc etc ....