I learned that the fastest way I'll ever learn a subject (whether or not it's a programming language, a financial derivative, or an era of Hinduism) is on my own, poring over search engines and worn-down books. Professors will never teach me faster than I can teach myself.
I learned that, yes, you're more or less paying for the piece of paper (but that doesn't mean there isn't a lot of other awesome things you get along the way.)
I learned that, yes, that piece of paper is quite worth it, no matter how many hip tech companies say they don't care about pieces of paper.
I learned that there can be infinitely more value in talking to a stranger for fifteen minutes than spending that time browsing Reddit (or playing a video game.)
I learned that, despite my protestations otherwise, I honestly do perform best when my outcome is quantified, curved, and compared to other people's outcomes.
I learned that everyone's college experience is wildly unique, too, as I benefitted from professors in both business and computer science classes who always rewarded creativity instead of stifling it.
(I don't mean to say that I disliked college. It was the best four years of my life. But the idea that the undergraduate experience is marvelous and the idea that the undergraduate experience needs a lot of fixing are not necessarily in contention with one another.)