Do you know why you could buy and sell physical gold in banks?
Banks do not make money by selling you gold coins. Why would they still do this kind of business?
Because they want you to think that the money we use still has something to do with gold. They want you to think 銀行 still has some gold and silver to back up the money supply.
this is not true, since 1971.
Almost all currencies of developed countries are backed by US dollar.
And US dollar has nothing to do with physical gold since 1971.
Then what is a US dollar? What give value to the US dollar?
US dollar is just a piece of debt. All dollars in the world are borrowed into existence. It could people\companies borrowing from banks or US government borrowing from central bank, i.e. The FEB. As long as the private sector or govrnment borrow more money, money supply increases. As long as they pay back more money than they borrow, money supply decreases. That's it.
And the whole world depends on this system in order to give value to everything.