The nicest European countries are fragile and can't handle immigration well at all. Just ask Sweden how their next 30 or so years are starting to look. France has entirely failed for decades at integrating their immigration populations, despite their vaunted welfare state. They're very mediocre at functional integration, whereas the US is the greatest by-design melting pot in world history.
Try immigrating into affluent nations like Canada, Australia, Germany, Norway, Finland, etc. They make it far more difficult than it is to come to the US (unless you're a top tier immigrant in terms of skill/wealth). The nicest countries love to use points systems or the equivalent to keep poorer, lower skilled people out.
Canada for example is 2% black and 3% Latin American. Anyone think that's an accident? There are roughly 3/4 of a billion Latin Americans in the Americas and somehow Canada is merely 3% Latin American. The huge Latin American immigration wave the US has seen over the past 40-50 years has been nearly entirely blocked by Canada. It's by design, they're xenophobic like the Europeans are, and they do everything they can to keep poor people out.
People will say: just look how amazing Norway or Germany are. It's a nice fantasy, because good luck becoming a citizen (maybe for the privileged HN crowd there's a chance).
Japan is amazing? Yeah ok, go try becoming a citizen there. Try integrating, try becoming Japanese (you can't).
So what the hell is the point of saying: xyz is so wonderful - if they're excluding by design and won't let you join?
Gee, Stanford, MIT and Harvard are amazing, every college should be like that.
The US remains moderately accessible, most of its peers are the exact opposite.