I had little knowledge of the essence of narcissism until very recently. Narcissists must believe they are always right, and great, and perfect and handsome and everything else, because the alternative is unimaginably hellish. To be wrong is not simply to be human, the narcissist feels it as humiliating, a sign of utter worthlessness and complete unworthiness to be loved.
Until I understood the merciless pressure that causes someone to see the world as a zero sum war zone, I could not grasp why a minor conflict with people who have long loved each other, seemingly so simple to resolve, was actually insoluble, why everything I did to make it better made it worse.
I also learned that narcissism may sometimes only be revealed during conflict. As long as things are nice, everything is beautiful. When there is conflict, oy. Any conflict with a narcissist, no matter how otherwise easy to resolve, is a deadly battle that must be fought to the death.