In brief, the far-ranging defense system of those blessed/cursed with a marked Narcissistic Personality Disorder (NPD) can be nothing short of massive and virtually impenetrable.
And this impenetrability is well worth noting. For it explains the immense frustration people experience when they have to interact with such an extreme narcissist—vs. one who has some narcissistic traits yet isn’t totally lacking in self-insight and the capacity for change. With the more destructive variety, however, the mere suggestion that something may be wrong with them can feel so threatening that they’ll be compelled to vehemently strike out, as though they’ve just been walloped with a searing poker.
And that’s almost inevitable when a narcissist has been so “bedeviled” by their Herculean defenses that their entire personality is reducible to them. As in, they’ve become their defenses. Which is why, once you get to know them, their reactions can feel so predictable. It’s regrettable but, like most sociopaths, many narcissists cannot be reached. Quite simply, they’re untreatable, their elaborate defenses preventing any external feedback or force from destabilizing their whole offensive manner of being.
And strangely, when stressful interpersonal situations intensify their defenses (and, given their hyper-reactivity, it doesn’t take much provocation for this to happen), they just become more verbally (and sometimes physically) violent. They don’t deteriorate into some form of psychosis, despite their mastery in, to use the vernacular, driving other people crazy.