I think part of your argument about learning from Khan Academy or 3blue1brown is highly predicated upon being in subjects that are widely known and studied, par

I think part of your argument about learning from Khan Academy or 3blue1brown is highly predicated upon being in subjects that are widely known and studied, particularly introductory mathematics/physics/engineering. I personally cannot speak for physicists, but I imagine it is similar as follows. One of the most valuable parts of a Engineering/Mathematics Degree (Both at the BS and the MS levels) is that of the upper division elective courses for specialization. At research universities, these classes often contain lots of information/techniques that can't be found in a textbook, let alone in a youtube video. At best, there might be a very cursory blog post, or a collection of research papers that you really aren't ready to explore on your own. Often, these classes result in final projects which can be expanded into research papers or portfolio projects with the professor teaching the class, both of which are valuable learning opportunities for the student and effective signaling mechanisms post-graduation. These classes are where the real technical value of a college education is found. In addition, there a quite a few classes which are offered if not required for such Engineering/Mathematics students which are pretty difficult to approach on your own and surmise in a short period of time. For examples, I point towards Analysis 1/2/Complex, PDEs, Dynamics, and Probabilistic Robotics. I personally got a lot from my undergrad, I (and this may only apply to me) strictly would not have succeeded in learning all the topics I did if my only motivation was my personal learning in my free time, particularly in the short time horizon I did. The pressure cooker (cough engineering school) I went through was very formative, built a number of professional/personal connections, and taught me almost all the personal and professional skills I have. This is just my 2 cents though.