Prior to the death of the Curtis boys' parents, the family was living a fairly conventional, middle-class lifestyle. Darry was a good student and a great football player, popular and on the road to a promising college career. Sadly, when the boys lost their parents in the car-train accident, Darry was forced--or at least chose to--take care of his younger brothers rather than risk them being separated and consigned to the foster care system. Ponyboy is aware of Darry's overnight exit out of the world of the social elite (Darry quit school and works construction full-time to keep the family together and fed)and feels guilty about it, even as he is irritated at Darry constantly being on his case about his curfew and homework. He knows that Darry is hoping that he (Ponyboy) will have the opportunities that he (Darry) missed out on.
He had a scholarship hinting towards a career but had to give it up for Soda and Pony.
Darry tries to keep Ponyboy on the straight and narrow by not letting him do poorly in school and become street trash. So he's keeping Ponyboy on a narrow path to doing good in school and focusing on all his abilities.