I was one of those students who didn’t care about the grade except as a proxy for learning. I never understood why other students would try to argue with profs about test grades, when it was clear they list points because they misunderstood something. That said, the thing that kept me from getting C’s in courses I didn’t like was that I was motivated to do at least decent at the things I do.
For the classes I sat in on, the motivation was that I was interested in the topic. But the social aspect really helped. Even though I wasn’t enrolled, knowing I was going through the same pain helped. I’m not surprised that MOOCs havn’t taken off like people assumed they would. There is nothing like sitting near people to really feel like doing something.