Tom gives up his own opportunities for advancement and adventure in order to support his family.  His tragic flaw is that he cannot fully accept the responsibility to act as the father, nor is he fully willing to walk away from the family to pursue his own goals.  He gets in trouble at work because he is distracted, but he isn't willing to walk away from the family and chase his own dreams until after he brings Jim home, and even then his description of events years after the story occurs demonstrate his inability to ever fully escape from the difficulties he faced at the time of the story's action.