Do you feel like you learned the material to a level that you would have had it been graded for you??
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.
Besides, of course, getting to bounce ideas off each other, etc.
Btw did you ask the profs if you could take the exams , and did you? Were they willing to? They are usually a little averse to extra work lol.
Do you actually just show up? Or do you have to audit the class and register, but for free?
The irritating thing nowadays is that sometimes materials are behind a wall on the university website.