As someone with a Ph.D. in clinical psychology, I can tell you that it’s the other way around: malignant narcissism is actually a flavor of a diagnosable psychological disorder, a personality disorder called Narcissistic Personality Disorder (NPD). NPD is very certainly a result of severe childhood trauma.

Sub-clinical forms of narcissism also play a part of mental health issues, and are also the result of trauma.

And yes, those who get tangled up in relationships with people who have NPD also usually have other constellations of personality disorder, if only ones that are more socially acceptable.