I guess you don't know much about foreign exchange, because China holds US dollar foreign exchange, and China is a RMB settlement area, so US dollar foreign exchange can't be used. As a result, huge amounts of foreign exchange cannot be used directly at home, but only through foreign trade. In foreign trade, because China is blocked by foreign technology, it is impossible to buy a large number of high-tech products from abroad, and food cannot be preserved for a long time, nor can it be purchased in large quantities. Because of the shortage of resources in the world, money can't be bought, and foreign exchange can't flow into this area in large quantities. If foreign exchange is used in domestic infrastructure, it is equivalent to exposing all domestic infrastructure to foreign enterprises, which will directly suppress the domestic infrastructure industry, so it is difficult for foreign exchange to play a role in this regard. In addition, the dollar has been depreciating against the RMB, which will cause great losses if it is not used. The best direction for China to use foreign exchange is the financial industry. Because of the high financial risk, it is impossible to invest in foreign exchange in these places, and you can only buy government bonds with the lowest risk. There is a widespread economic crisis in the world. As a result, only US Treasury bonds are in a better state, so we have no choice but to buy US Treasury bonds. In addition, because the economic and trade relations between the United States and China are too close, the so-called political risks do not affect the national debt as some people think, which gives more reasons to buy American national debt.