Here are some assumptions about Rock's past (in addition to what we already know)
he came from a rich family, he was the child of wealthy parents. However, her life seemed boring to her. Therefore, he most likely rubbed shoulders with a bad entourage. Street rebels with whom he expressed his rebellion against his intellectual background. He was rather hot-tempered and tried to prove to his new friends that he was not at all a pampered boy from a wealthy family. And he showed it with his fists, fighting. According to assumptions, one day, he would have gotten too carried away and would have perhaps accidentally killed a man in a fight, that's why he landed in prison.