If you're not a psychiatrist, then you don't have the training needed to diagnose someone with a mental disability. I don't care whether your parents actually have NPD or not, but the risk of armchair diagnosing someone is that you'll just amplify stereotypes. You diagnose them because they meet a stereotype, and then you study their behaviour and reach the conclusion that narcisstists act like the stereotype, and then you spread your conclusion. It's citogenesis.

Also "narc" when used to say someone has NPD is straight up a slur.