I think the two biggest mistakes the U.S. made in the 1990s were not helping Russia, which was struggling after the collapse of the Soviet Union, to establish a pro-American government and incorporate it as part of the West, and allowing China to join the WTO with the naïve belief that it would democratize, which led to China's economic miracle.
But Now I think I should also include the halting of the space program. The Moon contains its richest resources in rare earth elements. Because there is no atmosphere, the Sun provides unlimited, rare earth elements are accumulating on the lunar surface. Even, Only chemical and thermal processing is required, so large-scale environmental problems like those caused by mining rare earth elements on Earth do not occur.
The price the US paid for giving up space exploration was that it became China’s bitch lol