The narcissist's False Self requires constant dollops of narcissistic supply (attention.) The narcissist's sense of entitlement and innate superiority collide painfully with his unmitigated dependence on other people for the regulation of his labile sense of self-worth and the maintenance of his grandiose fantasies. Narcissists who are also psychopaths (antisocial) or schizoids choose to avoid the constant hurt and injuries entailed by this conflict by withdrawing from society -- physically as well as psychologically - into a cocoon of self-delusion, confabulated narratives, and vivid dreams of triumph and revenge. They become "lone wolf" narcissists and prey on society at large by indiscriminately victimizing, abusing, and attacking any person unfortunate enough to cross their path.
Inevitably, the lone wolf narcissist is in a constant state of deficient narcissistic supply, very much like a junkie deprived of access to his drug of choice. This overwhelming, unquenched, vampiric hunger coupled with an almost-psychotic state render the lone wolf narcissist dangerous to others. His aggression often turns to outright violence; his frustration to vindictive rage; his addiction to narcissistic supply drives him to coerce people -- often randomly selected -- to serve as sources of adulation, affirmation, and support; his detachment evolves into a loss of touch with reality, cognitive deficits, and utter misjudgement of his environment and milieu; he seeks fame and celebrity by all means available to him, even by resorting to crime and terrorism.
(From the book "Malignant Self-love: Narcissism Revisited" by Sam Vaknin - Click on this link to purchase the print book, or 16 e-books, or 3 DVDs with 16 hours of video lectures on narcissists, psychopaths, and abuse in relationships: http://www.narcissistic-abuse.com/the...)