>As measured by prosperity life in the US is better; the poorest US state has a higher GDP per capita than most western European countries.

GDP per capita/prosperity is a poor proxy for quality of life. The US is lagging most of the developed world in most quality of life metrics, even as reported by US news outlets, which don't rank the US in even the top 20: https://www.usnews.com/news/best-countries/rankings/quality-...

>Americans have bigger houses, more food, bigger cars,

The size of one's house or car is at best weakly-correlated with quality of life. I would rather not own a car at all and be able to walk everywhere, rather than spend hours of my life commuting in a gigantic SUV.

>bigger salaries, and access to better medical care and schools if they've got an okay job.

The US ranks the lowest in the developed world for life expectancy, and among the highest in obesity globally (obesity being a major determinant of health). The US remains the only developed country where an unlucky dice roll (e.g. genetic-linked cancer) will bankrupt you and destroy the livelihoods of your children.

This is not the flex you think it is.