The big difference is the discussions with a group of other people (especially great: of different majors!) and a professor who knows what you're talking about

The big difference is the discussions with a group of other people (especially great: of different majors!) and a professor who knows what you're talking about and how to steer the conversation. Trying to understand a book and trying to understand people is very different. I had a great seminar this semester where we would talk about "knowledge" from a philosophical, historical, theological and physical point of view with the respective students and professors. Often, we were none the wiser about our original question afterwards, but had had a great discussion, and quoting the philosophy professor, "understood the question better". Again, my point - it is not about gained knowledge, and the way a conversation engages your mind is hard to replicate with a book. But then, I live in Germany and can live off 6000€ including university costs for a year, so YMMV.