Psychologists and sociologists have studied the phenomenon of sports fan violence and have found some interesting answers. Researchers attribute violent behavior to a heady mixture of factors: intense fan identification with a team, behavioral changes when people become part of a mob, and strong psychological and physiological responses when your team wins or loses.
And when American sports fans riot, it is almost always in celebration of a victory rather than a defeat.
People often split themselves into categories based on occupation, ethnicity, gender or other factors. Unlike race or gender, over which people have no choice, sports fandom is like a religion: It’s self-selecting but also strongly influenced by the environment, including family and other people with whom you grow up.
That sense of belonging it bestows can often be beneficial. In studies on college students, Wann has found that fans who identify strongly with a team often are less likely to feel lonely or alienated and have higher self-esteem.
William Wan and Amy Ellis Nutt, Washington Post, February 5, 2018