Poor availability of introductory learning materials for grad-level study. Undergrad level stuff is pretty well covered by whatever MOOC you can imagine. But often for more advanced topics there is a large gap between what you know after an undergrad degree and what existing learning materials (if any exist) assume you know. Sometimes you just have to bang your head against papers until your brain melds with the concepts.

It’s understandable why this is. Writing introductory textbooks in your area of study is not prestigious work valued by your peers, takes a huge amount of time, and rarely makes money.

Perhaps the learning materials do exist, but there is no easy way to divine their existence. Expert-curated learning tracks might be valuable here. I’ll tell you what is not valuable, though: giant lists of “learning resources” in a github README that have no particular relation or sorting order and that the author/maintainer has never personally read.

Perhaps the struggle is necessary for learning. I’ll never forget those times my mind finally makes by itself the leap to understanding, although I constantly forget whatever smoothed-down introductory learning material I have consumed in the past. Perhaps the solution is simply to hire a grad student for 1:1 tutoring at $50-$100/hr.