Suppose I want to convert Zimbabwean dollars into US dollars. Who will buy the Zimbabwean dollars from me? That is, why would they ever agree to change their valuable US dollars into the less valuable Zimbabwean dollars?
The only thing I can think of that would entice a buyer is charging a fee. (The fee would also be paid in Zimbabwean dollars because that is all I have). But even then, what will they now do with the Zimbabwean dollars? Aren't they now left with a pile of less liquid currency than they started out with. It seems to me that the buyer loses...
Is the government of Zimbabwe responsible for meeting the demand of its citizens (indirectly via banks) to convert Zimbabwean dollars into US dollars? Or is the retail sector the only one that performs this service?
A similar question arises with altcoins. When converting an altcoin to Bitcoin, who buys the altcoin using Bitcoins? That is, what incentive does the buyer of an altcoin have in order to give up the more liquid Bitcoin, for an unknown altcoin?