It's such a shame that the state can't support the education system financially, so that 20-year old people wouldn't have to take loans to study. It works in other countries, so why not in the US?
The simple and honest answer to your question is greed. The fact is that the USA has more than enough money to support a healthy and well-educated population through government-funded healthcare and education (including what you asked about - higher education), but the capture of significant portions of our government by corporate interests has successfully stopped that kind of progress from occurring so that an ever-shrinking number of people can become unfathomably wealthy. This has been accomplished primarily through the use of emotion-based propaganda over a series of decades and has been incredibly effective at poisoning the national discourse.
Federally guaranteed student loans exceed $120 billion every year. That is a massive subsidy, and it may be increasing costs for more people than it helps. The glut of admissions being able to pay artificially high tuitions is emboldening administrators to add more dormitories every year, expand the administrative class, and build rec centers -- raising tuition even further.
> Last year, FSA provided more than $120 billion in federal grants, loans, and work-study funds to approximately 13 million students at nearly 6,000 participating schools.
The damage from existing poorly designed government subsidies should be fixed before we issue any more blank checks - otherwise we'll all be stuck paying for artificially inflated university budgets.