...The article also mentions how "As researchers have dug deeper into the roots of rejection, they’ve found surprising evidence that the pain of being excluded is not so different from the pain of physical injury. Rejection also has serious implications for an individual’s psychological state and for society in general. Social rejection can influence emotion, cognition, and even physical health. Ostracized people sometimes become aggressive and can turn to violence. In 2003 Leary and colleagues analyzed 15 cases of school shooters, and found all but two suffered from social rejection..."
https://www.apa.org/monitor/2012/04/rejection