It is the exorbitant privilege. It is a bit hard to find good discussions of the mechanism because it gets political very quickly. But in essence if the US prints the whole world absorbs it, if Japan prints it stays in Japan.
When a central bank expands the money supply (by changing their interest rate or doing QE) it doesn't spread linearly in the economy. There is a much more complex pattern. And the dynamics of the dominant currency which has all other curencies subordinate to it are completely different from that of a mostly local currency.
But as I wrote. This is a controversial subject. And there are economists out there who will tell you that the special status of the US dollar makes no difference at all and this de Gaulle guy just was upset about losing some colonies.
You somehow think that the demand/supply curve is linear.
Why? It would be quite odd. Certainly Japan has generated far more currency and debt over the last 35 years while inflation stayed low (and the relative value of Yen stayed high). I don't see any explanation for that here any more than the yearly gyrations of other currencies crypto or fiat.
