(answering a different question) A lot of people are deciding they need to get a solid grasp of linear algebra, calc up thru some real analysis/measure theory,

(answering a different question) A lot of people are deciding they need to get a solid grasp of linear algebra, calc up thru some real analysis/measure theory, convex optimization, probability theory so they can read deep learning/machine learning paper. So there's meetups, study groups, subreddits to work thru different topics