The companies making those calls are just one part of an ecosystem feeding on federal student loans. There are also debt servicers, refinance lenders, firms that help former students stay out of default and for-profit schools that make money as borrowers try to repay more than $1.2 trillion in government-backed education debt."
It's literally the first and second paragraph of the article.
Then over the lifetime of the ex-student they pay back this "money" plus interest which destroys the principal and consumes existing "money".
It should be noted that the creation of the debt benefits "growth" in the present electoral cycle whilst the repayment occurs mostly in other electoral cycles.
Of course, that was before we were far into (sarcasm) The Golden Age of Reaganism - schools were more funded by tax money than loans, so the budgeting wasn't left up to the credit whims of 18 year olds. Tuition/fees went up quite a bit by '88, though still nothing like what we are paying for my daughter now.
http://biz.yahoo.com/e/151022/apol10-k.html
Which still fits in under cashing in, but there must be more to the story than for profits.