There is nothing to fix. You have an aging population that pays back loans and never takes any new ones on. This contracts the money supply. Business profitability shrinks as less people spend their money and more save it instead. Given a limited number of dollars saving cannot continue forever. At some point you have saved every dollar there is. The only way you can save even more money is by creating new dollars. It's an entirely human made problem. If you stop saving beyond the point where it makes sense the problem goes away.
Telling people to stop saving doesn't work because their decision to save is just the result of being at the end of their life. The other solution is to make the dollars real. E.g. by investing the money and letting the dollars in your bank account represent a physical resource somewhere on the planet. This approach suffers from a problem: Companies are saving as well. The interest rates on credit are too high to justify investments. You can just sit on cash for a risk free loss vs the uncertainty of investing into a market that is shrinking in profitability as people stop spending money. So the only answer left is to let the government take on the debt so the retiring people and companies don't have to.
If the government decides to be "financially (ir)responsible" it can just kick the problem back to the private sector by running a balanced budget or even a surplus. Without negative interest rates the problem will not resolve itself and zero sum games start dominating until the only acceptable solution is a war. At that point we get to decide whether we want to kill people in our country or go to another country and kill people there.