USD became the reserve currency in the Bretton Woods, when it was pegged to gold and major currencies were pegged to USD. This was pretty much demanded by US in the Bretton Woods conference.
In 1971 US unilaterally scrapped the Bretton Woods and essentially stole the gold reserves. Other countries protested heavily but could not really do much.
US then transitioned to the petrodollar system where demand for and value of the dollar is/was ensured by dollar monopoly in oil trade. This was done with deals with oil producing countries with varying levels of coercion.
Granted it is in a country's best interest not to piss off the world's largest military. Silver or lead is a decision too.
In 1971 US unilaterally scrapped the Bretton Woods and essentially stole the gold reserves. Other countries protested heavily but could not really do much.
US then transitioned to the petrodollar system where demand for and value of the dollar is/was ensured by dollar monopoly in oil trade. This was done with deals with oil producing countries with varying levels of coercion.
Granted it is in a country's best interest not to piss off the world's largest military. Silver or lead is a decision too.