They already know that the debts they are carrying are impossible to pay, it seems they think the day will never come when they will need to pay those debts, if things made sense the whole thing should have collapsed immediately but it did not, so it seems the faith they have about sustaining such a system is not so out of place after all.
of course when they are in debt there is a clear purpose and measurable calculation as well. because of the many debts and long periods of time, sometimes to bequeathed to the next generation. and the next generation needs debt to carry out the plan. and I think as long as for the right purpose, debt will not impoverish us