DB-TA
23 developed countries is not a narrow sample. I agree homogeneity is a factor. Japan and Sweden, not Portugal which is one of the poorer countries to live in. And the US, not blessed with homogeneity and thus should be a poor country in which to live, which it is.

Quality of life was not established by poll but by considering 11 factors physical health, mental health, drug abuse, education, imprisonment, obesity, social mobility, trust and community life, violence, teenage pregnancies, and child well-being.

Interesting your comment on income inequality and misery. Could you give some samples, knowing that this analysis applies to developed countries?

The government should not be accumulating debt to be paid off by economic growth. That is close to suicide.

I don't see the advantage of living next door  to an economic giant. Their technologies are available world wide. One undesirable feature is that we have imported violence from the US. Europeans have escaped that.