You can see that the income scale is actually logarithmic. Did that blog author even read the paper? Kind of ironic him throwing around Dunning Kruger references.
Anyway, the happiness definitely does level off at around $75k in the Kahneman and Deaton paper. It's just that other research shows happiness increasing beyond this point.
As I said, the conclusion remains the same. $50k->$70k is a huge boost, with a very practical impact (especially given some constant living costs), while e.g. $150k->$170k is a very gradual change.
