Then answer is simple: Federally Subsidized Student Loans
Student loans have made it so that almost anyone with a high school diploma can borrow money to go to college. Colleges are now in the business of competing for students who have effectively eliminated price as an object. Want to spend $14,000 per year on a college education? No worries. The feds will directly lend you the money to do this if you're an independent student.. Want to go to grad school, then you're limited to an additional $138,000.
What these student loans haven't done is better equip graduating high school students to succeed in college, or to get out of it what they should. So, what you wind up with are colleges catering to a large number of underqualified students pursuing degrees that prepare them to do absolutely nothing with the rest of their lives. When the colleges don't have to compete on price they don't have to worry about programs that do not "earn their keep." They don't have to worry about only offering that which is economically worthwhile offering, because they can raise prices and it doesn't effect their demand at all. Essentially in a competitive sphere you've removed any necessity to compete on one of the most important elements, price.
The well intentioned interference of our central planning government has caused runaway inflation. If you walked back the price of education to 1975 levels and applied the same rate of inflation as say, average wage growth, what you'll find is that the cost of college is not only well within reach, but something that could be payable in cash for even most middle class families with a modicum of forethought. It might mean that every college wouldn't have every conceivable major, and it might mean that some majors are condensed to only a handful of public universities in the state, but would that be so bad. I mean, how many public universities do we need to offer degrees in underwater basket weaving?
Just food for thought.