How much research have you done on "Psychobabble" before your dismissal of it?
I have done more research on narcissism than anyone and I do not fit the trope. For example my childhood was not abusive. If anything my parents encouraged and reminded me of my intelligence. Nothing happened to shatter any "true self" I have always been me. An idea I had is that my Asperger's may just manifest as narcissistic seeming but be part of that in some way.
sounds like developmental abuse. parents who make their child think they're amazing, intelligent, one of a kind when their kid is mediocre at best set them up for failure. it can also leads to the child have a narcissistic false image based on what their parents give them. in short, spoiling a child too much can cause it to become a narcissist the same way abuse would, look at blanc and tc.