Comment by DiogenesKynikos

The US was barely treading water militarily, at enormous cost in both lives and cash. It was not progressing towards its military and political goals. That's why the US public pulled the plug.

The US could have continued to tread water for another 5 years, or another 10 years, or another 15 years, and would have lost even more men and spent even more money, and it would still have faced the same problem: there was no way to win the war. Every day that the war continued just meant more deaths and more money wasted.