Frontiers in Psychology presents a study of those who participate in hate-full conduct on line and finds a common trait. The full report detailing the study’s methodology and findings is at the link; here’s a bit (emphasis added).
In the present study, we sought to investigate whether certain psychological characteristics can predict posting hating comments online. Our results showed that high scores on the Psychopathy subscale was a significant predictor of posting hating comments online; whereas age, sex, high scores on Frustration, Envy, narcissism, Machiavellianism, and Satisfaction with Life scales were non-significant predictors. Interestingly, high scores on the Scale of Envy almost reached a statistical significance (on the level of a strong trend).