If you have a giant pile of gold and no food in the middle of a famine, how wealthy does that make you? If someone's starving and they have a loaf of bread you could offer them all the gold in the world for it and they wouldn't take it. This is because gold has no intrinsic value.
Gold, just like paper money, has value because people think it has value. Neither can be used to provide a person with the things they need to survive, both must be traded for them. Gold is a monetary fiction just like paper money.
Silly. Historically, gold currency has always been breakable into silver, bronze, copper or other physical currency, just like our modern day $1, $5, $10, etc.
The point is, physical currency can survive a blackout, while currency that only exists in the form of 1s and 0s in a computer databank can vanish in an instant -- and that represents a whole hell of a lot of extracted terrestrial wealth, alongside countless hours of human labor that could be lost in an instant.