Based on my sample of 43 countries, proportional increases in per capita GDP can be expected to equal or exceed increases in life expectancy up to about $2,000 (over this range, increases in resource use, measured by per capita ecological footprint, also either exceed or equal increases in per capita GDP). For happiness, this number is around $4,000.
Break-even for per capita GDP and life expectancy is about $27,000 and break-even for per capita GDP and happiness is about $24,000. Break-even for per capita GDP and resource use is about $6,000.
This data implies that economic productivity, as currently measured, translates into meaningful changes in people’s lives over a very limited range.