First of all, the dollar is still the most widely circulated currency in the world.
We can't do international trade without dollars at present. Therefore, in order to maintain the smooth progress of international trade, a certain amount of US dollar foreign exchange reserves is necessary. Apart from China's surplus position in international trade, there is still a certain foreign exchange surplus every year, so we can't always hold the surplus dollars in our hands, can we? Moreover, these foreign currencies can't engage in venture capital, so they can only choose safe investment, so buying American debt has become the best choice. Buying some American debt is an investment, and even the smallest mosquito is meat.
Secondly, after holding US debt to a certain scale, the interests of the United States and creditor countries will converge.
For the United States, American debt is a way for dollars to return to the United States. But when holding American debt to a certain extent, it is equivalent to an atomic bomb, which can bind the interests of the United States and the country together. Therefore, holding a certain amount of American debt in China is equivalent to holding a nuclear weapon that can destroy the dollar system. In this way, the United States will have scruples when taking action, and if it reaches the point where the larger foe is broken, no one will feel better.
Finally, buying American debt can ease Sino-US relations.
Whether you admit it or not, we still have a long way to go with the United States, and the gap is not small in all aspects compared with the United States. It is obviously irrational to choose confrontation with the United States now, so peaceful development is the safest way at this time. Because our development speed is faster than that of the United States, the longer we delay, the smaller the distance between us and the United States will be. Buying American debt during this period can ease Sino-US relations and win us a longer development time.