The USA makes up about 5% of the global population and yet it consumes about 1/3 of the world's resources and emits about 30% of the worlds waste and pollution

So the world would be at the same state of affairs if there were 900 million Americans living on it OR if there were say 17 billion Indians living on it.

It sounds as if there are far too many US citizens on the planet. A simple distribution problem rather than a total global population issue