The US is not a good example, your social welfare is quite limited. Spending your youth in the US accumulating capital at a rapid speed and then moving to a "so

The US is not a good example, your social welfare is quite limited. Spending your youth in the US accumulating capital at a rapid speed and then moving to a "socialist country" like Sweden or France and living off your investments (bonus points if your new country does not tax foreign incomes) And you can literally vampirize everyone else, abusive a contributive welfare system without really contributing much. And that's just the tip of the iceberg, many citizens don't want to live with others from specific countries at a massive scale. The world would blend too much and become vastly uninteresting.