There are so many more systems than the USD. There's many more systems than money itself! There are industrial systems, food systems, logistical systems, educational systems, ethical systems, religious systems, political systems.

It's naive to think all those systems are subservient to some other "master" system, or that the fragility of those systems is multiplicative instead of offering complementary strengths. It's naive because none of those systems developed dependent on the other systems, nor were they independent; they've all been developing together for thousands of years. It's like an ecosystem of systems; if one fails (such as currency) then there's a dozen or more others that are ready to pick up the pieces. And it's myopic to think currency is even one of the more important systems, as though it's somehow more important than the other foundations of human experience that led us here.