This might be a nitpick, but this is a bad analogy. If you have $50k * 4 years sitting around to pay for it, sure, it's probably worth it. That's not how it works, though.
You have a giant pool of 17-18 year old kids with 0 assets and minimal skills. These kids, in general, need to borrow to go to school. If they have to borrow $50k/year for 4 years, that's $200k in loans, plus they graduate with accumulated interest over those 4 years.
The better analogy would be selling an 18 year old kid getting a loan for a $200k car that they get in 4 years. Where this isn't accurate is that after 4 years, you can repossess the car if they don't make payments. With a college degree, there is no tangible asset. If the kid decides after 4 years that he wants a bicycle, he can turn in the car. If after 4 years at Stanford, a person decides to do something that doesn't pay the bills, now what do you do?
And, since the loan is up-front, all of this risk has to be accounted for. Right now it means saying that the loans can't (easily) be discharged. To me this seems somewhat fair, with the argument being that nobody forced the kid to go to Stanford (pay $200k for the Porsche), they could have gone to some state school (the used honda civic).