The benefit of education is not simply a long-term financial reward for those prepared, or wealthy enough, to take on a commercial risk early in life. It is a benefit to the community as a whole, and as a community we should be prepared to pay for it.
It is in all our interests that there are enough doctors, engineers and teachers, when we need professional assistance. It is also in our interests that we have a community with an appreciation of social issues, as well as science and technology, able to make balanced judgments. I would prefer to buy my Big Mac from a history graduate, than there to be no history graduates at all.