Propaganda, it's as simple as that.
Most of us even in the West see the USA as the land of Milk and Honey, Hollywood shows us us great it is and even your super accurate Anon Babble has Americans telling us that their poorest state (Mississippi) has a higher GDP than Britain and is better???
I have been to the States on 5 separate occasions (once was holiday in Florida so I will ignore that).
I have been to 3 different states on work related business and the poverty there is 'Grimsby tier'. Most of them live hand to mouth, work multiple jobs and owe shitloads.
They lie about their income on Anon Babble, infact Americans are inherent liars about their wealth in general, if you believe them, then bigger fool you.
Many immigrants to America actually regret it, it's not as brilliant as they have been led to believe but they stay for the Gibs.