It is easier to predict spending. It is hard to predict interest rates. When nobody is willing to buy our debt, the rate will skyrocket and therefore, so will our total debt and interest payments. I suspect, the Fed will print and buy to try to avoid that, but then the US dollar will plummet in purchasing power making everything worse. It will be ugly. It will be so important to have things of value, ie. paid off house, tools, garden skills, BTC, gold/silver, etc.