“the greatest country in the world.”

I think more precise would be to say “the country that thinks of itself as the greatest country in the world”.

As someone said, we have the World Series but don't invite any other countries.

The 30 teams in MLB are by far the best in the world, and have many players from every country where baseball is popular.

If the English Premier League were so dominant that it were nearly impossible for any team from any other league to compete with them, it wouldn't really bother me if they called their winner the World Champion soccer club.

No doubt, but it seems like it'd be more sporting to allow the best non-US team to compete in the playoffs, if only as a friendly gesture.

We invite Canada every once in a while. And, man, I still think of that Joe Carter home run every time I see a Blue Jays logo.

Many Americans probably don't consider Canada as an "other country". :-)

Heck, they don't even have their own country code for dialing...

The US is objectively not the greatest country in the world. We are at a very high level of development on some metrics, and a medium-to-high level on others, but certainly not uniformly #1.

There is and can’t be a “greatest” country. That depends on individual preferences.

Seems like people took "greatest country in the world" a little more seriously than was intended...