Most spree shooters are loners. They are either schizoid (with deficient interpersonal skills) or paranoid and even paranoid-schizophrenic (psychotic, delusional). Their dysfunction is all-pervasive. Their family life, career, romantic relationships, professional and material accomplishments are all adversely affected by their mental mayhem. They feel excluded and shunned and are profoundly ashamed of, and frustrated with, their inadequacies and with their sadistic, self-destructive, suicidal, and self-defeating "inner judge" (inner, introjected "voices" or narrative). This frustration builds up and results in pent-up aggression, which ultimately manifests as furious, uncontrollable rage. The typical spree shooter is in love with all things violent: guns, the military, police work, virulent racism, and crime.
Since spree shooters have no one to share their emotions with, these tectonic and volcanic shifts get shunted (displaced). When the spree shooter seeks to explain to himself why they are so constantly angry, they blames it upon their ultimate victims and their behavior or idiosyncrasies. Members of despised minorities (Roma, Jews, blacks, homosexuals, etc.) are perfect scapegoats because their persecution is socially-sanctioned and the spree shooter catches two birds with one shotgun: for the first time in their life they feels that they "belong", that their conduct is socially-acceptable and peer-condoned; and they vents their fury on easy, vulnerable, risk-free targets.
During the attack, the spree shooter feels elated and their anxiety relieved. Contrary to the persistent myth, the shooter is aware of his environment, but they suspend morality, judgment, and the sense of danger. The shooter usually takes their own life as an act of defiance, not of desperation, rendering them out of the reach of the law. It is a grandiose gesture, sort of "Twilight of the Gods". At the same time, self-annihilation tends to uphold the shooter's view of themselves as "worthless", a sempiternal loser and an incorrigible failure.
The timing of the spree shooting is usually determined by a life crisis: losing one's job, divorce, incarceration, personal bankruptcy, the death of a loved one or significant other. The spree shooter often hits rock bottom before they erupt.
Healthy narcissism is common in adolescents. Their narcissistic defenses help them cope with the anxieties and fears engendered by the demands and challenges of modern society: leaving home, going to college, sexual performance, marriage, and other rites of passage. There is nothing wrong with healthy narcissism. It sustains the adolescent in a critical time of their life and shields them from emotional injuries.
Still, in certain circumstances, healthy narcissism can transform into a malignant form, destructive to self and to others.
Adolescents who are consistently mocked and bullied by peers, role models, and socialisation agents (teachers, coaches, parents, etc.,) are prone to find succor in grandiose fantasies of omnipotence and omniscience. To sustain these personal myths, they may resort to violence and counter-bullying.
The same applies to youths who feel deprived, underestimated, discriminated against, or at a dead end. They are likely to evoke narcissistic defenses to fend off the constant hurt and to achieve self-sufficient and self-contained emotional gratification.
Finally, pampered adolescents, who serve as mere extensions of their smothering parents and their unrealistic expectations are equally liable to develop grandiosity and a sense of entitlement incommensurate with their real-life achievements. When frustrated they become aggressive.
This propensity to other-directed violence is further exacerbated by what Lasch called "The Culture of Narcissism". We live in a civilisation that condones and positively encourages malignant individualism, bad hero worship, exploitativeness, inane ambitiousness, and the atomisation of social structures and support networks. Alienation is a hallmark of our age, not only among youngsters.
When societies turn anomic, under both external and internal pressures (terrorism, crime, civil unrest, religious strife, economic crises, immigration, widespread job insecurity, war, rampant corruption, etc.,) narcissists tend to become violent. This is because communities in anomic states offer little by way of externally-imposed impulse control and regulation, penal discipline, and rewards for conformity and “good behavior". Narcissists in such settings of disintegration become serial and mass killers on a greater or smaller scale than Hitler.