That chart doesn't support your claim that higher household income isn't reflected in happiness scores. Multiple factors are at play in those scores. The report mentions a few, but I couldn't find how much each correlates with the self-reported life evaluation.
As a funny BTW, the country used in this thread as a direct comparison, Germany, is indistinguishable from the US in this table.
His point was that it's not the only factor, and if you read that paper he cited there is a breakdown of exactly what factors contributed to happiness.
A social support network was one of the highest ranked, much higher than GDP per capita (the wealth of a nation, which can be used as a proxy for personal income if you have a Gini index to weight it against).
Finland comes out well ahead even if you weight it against Gini, and Finnish developers aren't earning more than US folks by a country mile.
[1] https://happiness-report.s3.amazonaws.com/2023/WHR+23.pdf