Narcissistic rage begins when a person is not accepted for who they are, for their natural state of being. Instead, they are valued when they meets the needs of the caretaker. The caretaker does not do this with malice but is simply replicating their own childhood. They see this as natural, appropriate and positive child rearing. But for the child, this is a negation and a denial of who they are and is likely the source of original rage. This is the genesis of the core belief about being “not good enough,” that the self is somehow found wanting. This original narcissistic injury is denied and repressed but can be triggered when a new injury presses upon it.
Lest this be taken out of context, this does not mean there are no limits placed on children. It does mean that love is not withheld as a means of changing a child's behavior. And that being loved is not conditional upon meeting the emotional needs of the caretaker.
The emotionally numbed actually have advantages when going out into the wider world. The sense of superiority, superficial confidence and competitive nature make it likely that they will have sufficient means to gain social acceptance. And while the rage can be triggered by a undermining their imagined superiority, it can be especially intense when an intimate partner threatens to leave or actually leaves. Then, the abandonment terror can trigger a dangerous escalation. The pain of the original sacrifice of the true self combined with the frustration that even after that sacrifice, abandonment cannot be prevented, can be overwhelming. It can disrupt the equilibrium that numbness had maintained and cause all the original anger to resurface, with potentially violent consequences.
The emotionally overwhelmed face different challenges. Fears of abandonment, self doubt and with no protective illusions of superiority makes them markedly more vulnerable. When they go out into the wider world, they are more likely to targeted for abuse by those who view vulnerability in others as a risk free way to discharge their anger (aka, bullies).
That does not mean that the rage is repressed. Rather, it tends to emerge witin the context of stable relationships, often as "innocent" remarks or behaviors, that are "misunderstood." If the anger implied in these communications is pointed out, what results is that rage being directed at the self, followed by some degree of emotional collapse.
Emotional collapse serves a number of purposes:
Those who were raised with social skills have dramatic advantage over those who were not. They can form social connections (team sports, close friends, etc.) that can function to keep the rage from their early experiences at bay. If that proves insufficient, they can utilize alcohol, drugs, eating, compulsive work, etc to numb or avoid those feelings.
Those who were raised without social skills can present the greatest risk, both to themselves and others. They were not accepted for who they are at the start of their lives and as they branch out into the world, that trauma will be re-enacted. Lacking the skills to connect socially, they will re-experience, in a most painful form, a renewed rejection. It is this group that is most likely to lash out, not against a single individual, but against society at large. This injury, pressed atop the earliest injury, is expressed in the last journal entry of the Columbine shooter Eric Harris (who killed 13 of his classmates):
"I hate you people for leaving me out of so many fun things. And no don't … say, 'Well that's your fault,' because it isn't, you people had my phone number, and I asked and all, but no. No no no don't let the weird-looking Eric KID come along." (Wikipedia)
False self - a persona or mask consisting of emotions (or lack of) and behaviors developed to meet the needs of the original caretaker.
Trigger - a current incident that is reminiscent of a prior emotional injury, which results in a disproportionate and intense emotional response.
True self - the spontaneous expression of emotion and individuality