> In a crisis you can't eat dollars, gold, oil, or bitcoin

But you can easily trade dollars for stuff Americans will sell you. That's the advantage of a national backer. In a crisis, they'll welcome the influx of capital in exchange for goods and services. Precisely what you need it you want to spend it.

This is why sanctions fuck up reserve calculations. If, in a crisis, America will sanction you, you might as well have held gold or Bitcoin.