Earlier quoted context omitted.
Think of it this way. Your parents borrow $10000 to throw a big party--one that you were not allowed to attend. After they die, their wills are read, bequeathing unto you $10000 in festivity debt, plus 50 years of interest. They never paid for the party, despite having such a great time at it (or so you assume, not having been there to judge). Now you have a choice. You can try to maintain the postmortem reputations…
There's another way of looking at it. Debt can be an investment. Compare the rates of inflation vs. the interest rates on bonds. Please let me know if I'm wrong, but... isn't the government making money with them at this point?
Don't presume that the government is necessarily using the sale of lower-interest bonds to pay off the principal on its higher-interest debts.
https://www.washingtonpost.com/news/wonk/wp/2013/03/05/john-...
As long as the principal on the bond cannot be repaid out of actual revenues, every bond you sell at a negative yield is one that may have to be refinanced at a positive yield later.