You can say exactly the same about diamonds and also about whiskey. What is the use of diamonds and whiskey?
From your point of view, to mine diamonds and make whiskey, these are stupid occupations that do not work.
But people like diamonds and whiskey. Similarly, people like gold.
The world financial system based on gold did not emerge because this system was appointed by decree, military force or deceit.
The global financial system based on gold arose because people like gold. The word gold occurs in the Bible about 400 times.
But the Bible does not say anything about the US dollar or Bitcoin.