This is determined by China's national conditions. China implements the system of compulsory settlement and sale of foreign exchange. Foreign investment, foreign trade, personal remittance and other foreign currencies must be converted into RMB with domestic banks when remitted to China. That is, foreign currencies such as US dollars must be taken to the bank to be converted into RMB for domestic use or deposited in the bank; Then there will be more and more foreign currency in the bank, so it is necessary to preserve and increase the value of foreign capital. The United States and other countries are world powers, and the national debt issued by them has high security and stable income; Therefore, China needs to buy these bonds.

The dollar is the world currency, and foreign trade settlement is settled in dollars!

The United States has a certain amount of money when it prints dollars. If there is more, it means inflation; if there is less, it means deflation. However, after these dollars are paid to China, the amount of money in the United States will decrease, so it is necessary to send the dollars back to the United States through a certain mechanism.

In order to ensure the balance of the total amount of money, otherwise the United States will have to open a printing machine to print money!

The dollar is the main currency of foreign exchange reserves in various countries. The United States is the most powerful country in economy, military, science and technology and culture in the world, and it is the locomotive of the world economy. People have confidence in the United States before storing dollars and dollar assets. In the short term, this pattern will not change.

There are two mechanisms for bringing dollars back to the United States:

One is to spend money on American products, but the United States can only sell American agricultural products and Boeing aircraft, and this money can't be spent! ?

The other is saving money, and this mechanism is US Treasury bonds!

Besides gold, gold in the world is basically in the hands of central banks, and there are not many in circulation in the market. Most of the gold is in the hands of the United States, Britain and France, and you can't buy it if you want! Moreover, both gold and currency are fishing now and cannot represent the total amount of money. The total amount of money far exceeds the gold reserves. The stability of a country's currency is no longer determined by gold reserves, but by national credit!