Then I'll go to a guy that will give me 300 loaves for that ounce, like the bank down the street.
See, my bread has an intrinsic value. If I want rice, I can trade my loaves of bread for rice. If I desire wood for warmth, I can trade my bread for my friend's wood. I can trade some of that wood for another neighbor's coat. I can trade some of my excess rice for a butchered chicken. Essential products have value. Paper currency has value, because it is divisible, measurable and easily exchangable. Gold is shiny and yellow.
And worth $300+. And in an emergency, it would be exchangabe for necessities, because people that owned just paper, whether stock or fiat currency would have nothing to carry as money, just big heavy stuff to barter. The only stuff they would be left with is the stuff on their property and all of that stuff depreciates. Gold does not depreciate on average and would suddenly be worth a lot more in a world without the U.S. dollar.
If you are on the brink of starvation, my loaf of bread is worth 10,000 ounces of your yellow metal.
Then I go to the farmer down the road who has a bin full of wheat and is willing to charge a reasonable price for it. What do you do in this situation? You eat your loaf of bread during the day, burn your now worthless fiat money for heat during the night, go to that farmer the next day to beg for wheat instead of buy the wheat like I did, or barter away the much-depreciated shirt off your back for it.