A currency is what is accepted as a currency by enough number of people. It's not like the US Dollars or any other nation's currency has any 'intrinsic' value, they are just pieces of paper stamped by the governments as well. The intrinsic value of a currency is always brought on by the economic value generated by the people who are exchanging the currency as a mode of payment and not by the currency itself.

Warren is a smart man, definitely a lot smarter and wiser than me, but anyone needs to put in the time to understand and contemplate before they go about making statements.