The US dollar has been the world's reserve currency since the Bretton Woods agreement in 1944. The dollar's share of global reserves has declined in recent years from 73% in 2001 to about 59% recently. However, it still remains far above the euro at 20.5%. Russia's invasion of Ukraine which prompted US to impose heavy financial sanctions on Russia, including freezing the country's central bank reserves, has alarmed some countries into considering alternatives to holding dollar reserves.

How has the US benefited from the dollar serving as the main reserve currency of the world? What are the threats of the Chinese yuan or cryptocurrencies like Bitcoin replacing the dollar as a world reserve currency?