[KirinDave]

It's not though. You don't "default" but your currency has to be well managed to a certain degree. The Dollar exists as it does because of its status as a reserve currency and because of how the Yuan is pinned relative to it.

You could break it. It's not immune to the hyperinflation that's hit other currencies.

Historically, the only other proposed option was the EU and much as been made about unsustainable financial policy there (many allege these issues are overblown to help discredit the notion of a strong Euro, but that's neither here nor there). But now we're starting to talk about creating to-order currencies with arbitrary properties, guaranteed supply limits and curiously popular ownership policies.

While governments will never give up the power to mint their own currency, it's not unimaginable that in 10 years some some countries will seriously consider participating in a digital reserve.