A lawyer ticked off a loud mobile-phone user for spoiling his movie, but the latter also felt he was exercising his right to chat while enjoying the same movie. It ended in a brawl. This rage of entitlement are also featured commonly in road disputes. Whenever they feel their status has been mocked in front of their peer group, the only resort is to flash their fists and beat the challenger to a pulp, in order to emerge the dominant person. This captures the anger of those directed at others for not abiding by set norms.
People can get addicted to their own anger.
Like gamblers who play with progressively higher stakes, they need to get a greater 'high' in order to get the same adrenalin level moving. Their rage can graduate from first shouting abuse, to hitting others and, maybe in the later stages, even manslaughter. In many people's minds.