It is an elusive, ever receding target. Narcissism is a healthy thing. It has gradations. But Narcissists have NO or very little personality. That's why they need others, dependent on them for their very self definition.
Narcissism is an exaggeration, a malignancy of a healthy phenomenon.
Self Love helps us survival. It is a prerequisite. But when overdone and when derived exclusively from the outside, it is malignant, it kills, emotionally. If not reflected by others, he feels annulled, dead, void. It is like being separated to molecules and suspended in mid air.