The Freakonomics podcast “Is college worth it?” was sadly centered on the economic returns of studying and on US colleges, but one student of economics and philosophy had this universally applicable answer:
If a bunch of people from the community sat in a park every day for three months straight and just exchanged books and had lectures, we’d learn much more than we had in three years here.
That’s a very good answer. Of course it depends on the university, the specific degree, the professor, but this student has a valid point.
Sure, you will know more after studying for three or four years than you knew before, but the real question is if you learned more than you would have learned on your own – or by other means – in the same time. I dare to say that most universities probably fail that test.