I completed the Stanford AI course, recently did a course in communications from the University of Amsterdam. In both cases, time management was a problem for me, I simply had other things to do, and drifted away... catching back up in the nick of time. Trying to fit distance learning into the regular schedule of campus life seems to be the problem here... it is definitely not the depth of material that is any kind of a stopper.
I think that guided deep dives into topics we would otherwise not understand, is going to be how we keep accumulating knowledge as a species in the future. Deep diving takes time, and unlike the real diving... it doesn't all have to happen in one shot.
On a side note... it is worth at least $20 to me... possibly much more... if someone can give me the deep dive that results in me understanding the Higgs field, and the Higgs particle. A true understanding... not some vague notion of mexican hats and potential.