Recipe for a Narcissist- Half Baked or Extra Crispy?

What makes a person deelop narcissistic personality disorder? We all have a healthy dose of narcissism, but how is a malignant, pathological one made? One that has no remorse, accountability, morals, love, or attachment to anyone. One that creates a false persona and wears a mask 24/7 that could fool even the most brilliant expert. One that cannot create a decent or stable life, self-sabotages, is reckless and impulsive, and always plays the victim?  How do you make one of those?