Historically, 1944 After the establishment of the Bretton Woods system with the US dollar as the international monetary system, all countries maintained a fixed exchange rate system. To put it bluntly, it is because the United States has strong economic strength and rich foreign exchange gold reserves.
However, with the intensification of inflation in the United States, western countries abandoned the fixed exchange rate system and adopted the floating exchange rate system.
As for Thailand's amendment, I am not sure, but as far as the example of the United States is concerned. I think it should be that we Soros took away the hot money, which led to the shortage of foreign exchange reserves in Thailand. And changed to a floating exchange rate system.