Cyberbullying and trolling.
Perhaps the least surprising behavior narcissists engage in online is cyberbullying and trolling. Narcissists online enjoy bullying others and derive a sadistic sense of pleasure in doing so. They post provocative comments, disturbing threats, and mindblowingly cruel insults. They have long histories of serial cyberbullying, much of which should warrant prison time. These are the “professional” trolls whose online identities exist purely for the purpose of taunting others, especially those who are already marginalized.
Research has shown that those who enjoy trolling also happen to have high levels of narcissism, sadism, psychopathy and Machiavellianism, known as the Dark Tetrad of personality (Buckels, Trapnell & Paulhus, 2014).This means that the same narcissists and psychopaths you encounter in real life could very well also be doling out their abuse behind the computer screen.
An even more recent study revealed that while trolls have the cognitive empathy to assess how someone might feel about their insulting comments, they lack the affective empathy to actually care about how that other person might feel (Sest & March, 2017). The same study showed that higher levels of sadism and psychopathy predicted trolling behavior. The higher someone scored on psychopathy, the more likely they were able to recognize and provoke the suffering of their victims but remain emotionally indifferent to it.Unsurprisingly, the same conclusion about cognitive empathy versus affective empathy has been shown for narcissists in another study (Wai & Tiliopoulos, 2012).
In short? The reason trolls and cyberbullies are able to abuse others so effectively (or at the very least persistently) is because they derive a sick sense of pleasure from harming others and do not suffer any negative emotional consequences themselves from inflicting pain. While not all trolls are created equal, those who are psychopathic and narcissistic are psychologically dangerous to those they target.