I have a lot of people saying "Money is actually worthless paper. Why do we bother even using it?"
Now I know that's not what you're saying, don't take me the wrong way for saying that.
But money in and of itself is a very useful thing to have.
If we only bartered in the things that had an actual use, we would barter in many different things.
From metal to food, to medicine, to clothing, to cars, etc.
Ultimately, there will be a time where you desperately need something, but since nobody needs what you're trading, you can't get it.
Say you need medicine. Badly. But all you have is stockpiles of food because you just harvested everything you needed.
You go to get medicine, but nobody will trade with you because they don't need food.
Ultimately, the fluctuations of value will be extreme, because some people will be more desperate than others.
While you might be willing to trade 5 pounds of food for the medicine, someone more desperate might be willing to pay 20 pounds of food for it.
But then someone with a twenty-foot roll of copper wire that the man selling the medicine needs much more than food.
So he takes the copper wire and you're stuck with your food, no medicine, and have wasted plenty of time.
And don't even get me started on how badly inequality would be. Do you realize how hard it is to trade houses for food/belongings? Most people would only get to rent with a monthly quota, while the landowners get a very easy living. They need only demand what they need.
And paying taxes as well. How would you do that? Collect a different item from each region?
And what about minimum wage? How is that decided when the value of items can fluctuate by 200% every hour, let alone 5% in 7 years.
The value of money is in its usefulness. You can look at the rarity of an item alongside with the usefulness.
Just because it has no practical use, doesn't make something not useful.
But there will always be the hippy who says there is no value to money and we should ignore it.
I'd rather not because those people have no idea what they're talking about.