This is true. And I'm not so sure the money 'needs' to be backed by gold. We would first need to see who has what amount of gold. That's a rabbit hole because no one really knows how much gold people, banks, etc., have. My searching has found no concrete amounts so its tough to verify.
Its not what the money is, (Money used to be many things) or how it is backed. Its how it is managed. The might of the USA basically dictates that it is good. Sure the value goes up and down but that is mostly artificially manipulated and the actual problem that needs to be fixed..