I knew narcissism was only to defend myself.

But yes, I totally agree it's nothing but a defense mechanism.
Narcissism works by their ego to go over someone else to feel reassured and "in place" of their own intentions.

But a classic narc trait is exhibitionism (not whipping out your **** in public)
This trait refers to a person's need to be the center of attention, and willingness to ensure they are the center of attention (even at the expense of others' needs).

How is needing to be the center of attention a defense mechanism?
There are different ways to look at this and my way is that self-desire isn't a defense mechanism but the primal sense of superiority is.