If universities only sold knowledge, public libraries would be out of business. Ideally, a diploma would be a rough estimate of one's knowledge. Theoretically, a 4.0 student knows more than a 3.0 student... theoretically! Most people do not care about knowledge, they care about a piece of paper that allows them to work, make money, support their families, and finance their vices.

Many of my former EE classmates ended up going into business, consulting, banking... and I am sure it wasn't their expertise on analog VLSI or DSP that landed them the positions, it was a piece of paper with a lot of good grades that, essentially, said: "I can be an obedient worker, I will put in the long hours without questioning the status quo, and I react to carrots & sticks".

If you actually care about knowledge, you can learn a tremendous lot in 4 years, but don't assume that most people are like you, because they aren't. Except if you go to Caltech or MIT, of course, but the girls are ugly and the parties suck at such schools...