you miss a point--there will be certain players whose opportunity cost will be higher than waiting for others to liquidate theirs. Those people will liquidate theirs for USD to do productive investment that will earn returns far beyond just playing chicken with the rest of the people to see who will circulate theirs first.

So it's not a tragedy of the commons situation--it will make perfect economic sense for certain people, if the hoarding gets too extreme, to change their currency for USD or other assets.