A country cannot have a widely distrusted currency for long, because everyone will do as you say (exchange away).This causes capital flight, so the gov't introd

A country cannot have a widely distrusted currency for long, because everyone will do as you say (exchange away).This causes capital flight, so the gov't introduces capital controls shortly thereafter. So the only way to do as you say is to be (far) more prescient than your peers. You need to be far more prescient because you have to beat the gov't insiders too. Also, prescience does not save your future earnings (I.e. after controls have been imposed) Or you take a risk and use the black market