From the Narcissism expert Sam Vaknin, PhD:
It is important to understand that the use of violence must be ego-syntonic. It must accord with the self-image of the narcissist. It must abet and sustain his grandiose fantasies and feed his sense of entitlement. It must conform with the narcissistic narrative.
Thus, a narcissist who regards himself as the benefactor of the poor, a member of the common folk, the representative of the disenfranchised, the champion of the dispossessed against the corrupt elite - is highly unlikely to use violence at first.
The pacific mask crumbles when the narcissist has become convinced that the very people he purported to speak for, his constituency, his grassroots fans, the prime sources of his narcissistic supply - have turned against him. At first, in a desperate effort to maintain the fiction underlying his chaotic personality, the narcissist strives to explain away the sudden reversal of sentiment. “The people are being duped by (the media, big industry, the military, the elite, etc.)”, “they don’t really know what they are doing”, “following a rude awakening, they will revert to form”, etc.
When these flimsy attempts to patch a tattered personal mythology fail - the narcissist is injured. Narcissistic injury inevitably leads to narcissistic rage and to a terrifying display of unbridled aggression. The pent-up frustration and hurt translate into devaluation. That which was previously idealized - is now discarded with contempt and hatred.
This primitive defense mechanism is called “splitting”. To the narcissist, things and people are either entirely bad (evil) or entirely good. He projects onto others his own shortcomings and negative emotions, thus becoming a totally good object. A narcissistic leader is likely to justify the butchering of his own people by claiming that they intended to kill him, undo the revolution, devastate the economy, or the country, etc.