There we were, in a world where USSR had collapsed, China not risen yet, with a USA as the uncontested dominant power. It has the unique chance in history to steer the world in one direction or the other.
Building international legal standards, multi-lateral cooperation, ensuring that whoever had the most power at one point would be limited by the world community, was something within US reach, and was a realistic hope. As a bonus, the first thing the community would work on would be tackling the climate change, as it was an obvious field where every country of planet earth had a common interest.
Instead, because of a few hundred "miscounted" votes in Florida, the US president was a zealous anti-intellectual evangelist, who decided that US interests trumps human rights, that denying climate change was a respectable political stance, and instead of spending a mountain of dollars on research, energy transition, diseases eradication, social net improvements, he spent it on invading 2 countries despite experts warning that it would not solve any problem.