J Government debt is a mechanism to use money from those who are rich to support those who are not

The Nomad How about getting some of that money back to pay down the national debt and benefit from the current exchange rate. No. It means there is no need to paydown. What you call "national debt" is J Government's debt, not Japan's debt. Its creditors are Japanese people, not foreigners. Japanese people who buy J Government bonds are making money by so doing via interests while J Government is using the money to support social security. In other words, J Government debt is a mechanism to use money from those who are rich to support those who are not - while increasing profits of the creditors. Japan, as a nation, is a net creditor, the world biggest net creditor. And this is the reason why Japan does not go bankrupt despite what you call "national debt".