Basically the US line will keep gradually dropping until widespread understanding of what Europe has already figured out: society needs more supportive mechanisms (healthcare, gun control, job security, low inequality, free higher education, walkable cities etc etc etc).
We are social animals. Individual happiness depends on your bank account, sure, but crucially also on your neighbor's happiness.
https://data.worldhappiness.report/chart
Basically the US line will keep gradually dropping until widespread understanding of what Europe has already figured out: society needs more supportive mechanisms (healthcare, gun control, job security, low inequality, free higher education, walkable cities etc etc etc).
We are social animals. Individual happiness depends on your bank account, sure, but crucially also on your neighbor's happiness.