I feel I learned more Math and Computer Science from books than from professors. However, under the pressure of a class, there's more motivation. Actually, when I got to Math grad school, the books weren't well written and the lectures were incomprehensible, so I didn't get much out of it.
Learning economics in school is a waste of time, when all the professors are trolls. Try asking an economic professor about the Compound Interest Paradox or "Is taxation theft?" He probably won't give a coherent answer.
When I first learned about the Black-Scholes formula, my reaction was "This is ****! I claim shenanigans!" I couldn't get anyone else to understand the inherent contradiction of the put/call parity formula. If your assumptions are wrong, no amound of calculation will get a conclusion that isn't nonsense.
If you want to learn to think like a troll, go to a university. If you want to learn the truth, read around and think for yourself.
If your goal is to work at a bank or hedge fund, then you need to learn troll economics. If you want to learn real economics, don't look in a university.
The bottom line is "What's more important to you? Knowledge or certification (piece of paper)?" If you value knowledge, a university isn't the optimal place to look. If you value certification, then a university degree will help convince other trolls that you're worth hiring.
If you're studying Math or Computer Science, a university may be somewhat beneficial. For other topics, it's probably a waste. However, you can save time and $$$$ by buying a book and reading it.