The Jormungandr of Public Debt
The only way that the government can pay off debts is through taxation, so that for it to borrow money is just a way of delaying either tax increases or austerity. Since the laborers can impossibly pay back all the money they earned for the work they did themselves, that money can only come from the investors who lent that money in the first place, either through extreme taxation or extreme employment. If the laborers are more powerful, it happens mostly through the former, leading to a rise of communist movements. If the investors are more powerful, it happens mostly through the latter, leading to a rise of fascist movements. If neither happens, a default looms, leading to a rise of anarchist movements. The use of debt is to delay paying when we cannot to a time when we can, not to avoid paying altogether to win the elections: as per Keynesian economics, which is the only thing that got us out of the last major crisis, we should surplus save during the Years of Plenty and deficit spend during Years of Famine, but we've been deficit spending throughout the Years of Plenty between the Great Depression and the Great Recession, making it impossible to spend any more, let alone to pay seventy years of debt in the foreseeable future.