[jollybean]

Just the opposite, during difficult times people rush to USD which bolsters 1 and 2.

That it's used widely and fungible is what gives it value.

If your own currency is destroyed, you use the one that has the most integrity that's relative to your country. For most nations the default would be USD. For Vietnam probably RMB. For Belarus either Euro or Rouble.

Then you develop integrity in governance and switch to a national currency.

A nations currency is actually a vert good measure of the competence and integrity of the leadership class.