There are lots of countries in the world that are less well off than the U.S. I have not made any claims about living conditions in those countries being worse or better than the U.S. I've not made any claims about people coming from poorer countries being dumb or even people coming from richer countries to the U.S. being dumb.

I made the claim that the U.S. is not as nice a place to live as many other rich countries. Objectively speaking this is a true statement. The U.S. ranks lower on many measurements of living standards. Of course there are counterexamples in that some people have a better standard of living in the U.S. than they did in another country but we need to be mindful that the plural of anecdote is not data.