And another way of looking at things is this problem would not exist if the government did not pass special rules that affect student loans, and only student loans.
I think there are lots of sources of failure that lead up to the problem, but the vast majority are of good intentions. It's not hard to see why the government decided to create special rules. It enabled lenders to all but completely ensure profit on loans meaning that anybody would have access to university, regardless of financial background. And that's a good thing.
Parents and teachers are also acting with good intentions. I would fully recommend college to anybody. I would certainly recommend move to Europe for it now a days, but the value of an education is immense. Access to the resources (physical, personnel, and intangible) of a campus is something that can open up vast new possibilities for an individual. And being around a more competitive group of individuals than you'd experience in high school can help ensure people stand a better chance of reaching their full potential.
And then there are employers. Today in the US it's somewhat paradoxical that we have a genuinely low unemployment rate yet also most decent job offers get more resumes than employers can handle. All other things being equal, a person with a college background is going to be more desirable than somebody without one. So why not require it and cut those CVs down to a more manageable size?
Perhaps the only people acting in bad faith are lenders. But like you mentioned they're just opportunists. And cognitive dissonance is a hell of a drug. They're not exploiting anybody. They're providing equal access to education for everybody in mutually beneficial agreements. At least that's what they'll convince themselves of.
What I'm getting at here is that trying to point fingers at one person or another isn't really productive. Who cares who's fault it is? There's a problem that needs fixing is all that matters.