The traditionally-held view is that there is an income (I've heard something like 70k in the USA) where the plot should become a horizontal line, i.e. increasin

The traditionally-held view is that there is an income (I've heard something like 70k in the USA) where the plot should become a horizontal line, i.e. increasing your income increases your happiness by zero. This might seem like a strange view, but the notion is not that money ceases to increase happiness, but rather increased happiness costs associated with earning that increased income start to negate the gains. Anyway, this graph is self-reported life satisfaction. We would need to examine the metric used in the studies that came up with the ~70k number to see if we can even compare the two studies.