In "The Outsiders", why wouldn't Darry ever become an old hood like some of the Brumly gang members?

In the novel "The Outsiders" Darry is the oldest brother of the Curtis boys.  Before his parents were killed in a car wreck he was a popular boy and captain of the football team.  He was very successful in school and only quit school so he could keep his family together.  This is not the personality of a "gang-banger."  Darry was mature and responsible. As Ponyboy notes,"Darry is to smart to hang around the greasers too long. "

Darry went to work, watched after his brothers, and did everything possible to keep his family together.  The Brumley gang was made up of losers who did not have any goals or direction.  Darry's goal was very important to him.  He would do whatever was necessary to save his family.  Darry was a hard working, driven young man.  These type of people eventually find success.