Why I don't feel satisfied from getting high grades in school anymore

Around 1-2 years ago I studied all the time in hopes of high grades in school because it was extremely satisfying. This died down a couple of months when I realized I studied just for the sake of grades. After this realization, I tried to understand what I was learning, most of the learning required questioning to properly understand, I tried to ask my teachers but they only tell you what they are required to tell you.

I now need to figure everything out myself because if I don't, I feel like a useless, incompetent piece of shit.

At this point, I'm only in school because my mother is traditional, she believes school is the only way to become successful in life. I'll just have to become self-sufficient financially so I won't have to go to school.