The USA spends as much on its military as all other nations on the earth combined. The USA has 12 aircraft carriers (no other nation has more than 3) and as many nuclear weapons as any other nation. We have more advanced tanks, planes, and missiles than all but a handful of nations. We can put troops in any country in the world on a few hours/days notice.
Our economy is the largest in the world and still growing. We have the best universities in the world. We have more patents than any country. We have some of the best minds. The primary language of the internet and business world is English.
We are the only hyperpower.
But that said, we cannot defeat the entire world in a military conflict, nor should we assume we will always be in such a powerful position.