It's evidence for more migration being permitted from places that are worse off. That is not evidence of greatness.

Out of the frying pan, into the fire.

I think if you visit a place like Australia you'll realize it's much more of a melting pot than here.

Believe it or not, you were raised by American education to believe this is the best country in the world. Take some trips, you'll change your mind if you get out into the world.