Boxing is a brutal and bloody sport, so it should be no surprise if boxers are cut from rougher cloth than the general citizenry. At the same time, to master the sport well enough to have any sort of professional career takes extreme self discipline and hours of technical training. So for a lot of reasons, a fighter is not your average cat.
At the same time, an individual sport like boxing attracts a wide array of personalities. True enough that a boxer is not your average type of person. But that doesn't mean there is any such thing as an average type of boxer.
Still, some fighters challenge the typical stereotypes about boxing more than others. Inside the ring they might be classic warriors in every detail. But away from the action, they have interests, or other careers, that you just wouldn't associate with a person who gets paid to beat people up.