I do not need convincing that narcissism/NPD exists. I have seen it, both personally and professionally. The mental health community was once divided on whether personality disorders exist and it is obvious why. All of us have unique personalities, with infinitely differing responses to infinitely variable people and environments and, therefore, to diagnose a personality as “disordered”, is only possible through the degree to which it differs from a non-existent “norm”. It is analogous to alcohol-everyone drinks it, at different times in different amounts, so proving alcohol dependency is more difficult than, say, schizophrenia where we do not all experience auditory hallucinations.