When the United States only had the atomic bomb, why didn't it take the opportunity to occupy the world?

The United States in your eyes: Why didn't it take the opportunity to occupy the world when it only had the atomic bomb?

The actual United States: Why should I occupy the world to let those backward areas enjoy an eight-hour workday, highly mechanized agriculture, free homeless meals with meat and drinks, and a minimum wage of $7.25 per hour? Do they deserve it?

The United States is not a charity. Once it occupies other places and makes them its territories, the treatment can't be too different from that of the United States.

Just like California and Texas, which were taken from Mexico, the economic level of these states is even better than those when they were independent.