Research on money and happiness often examines the logarithmic association between happiness and Log(income), a concept frequently overlooked. In a large U.S. sample, average happiness rose almost linearly with Log(income) from $10,000/y to over $500,000/y, with correlations of 0.98-0.99.

This linear association implies diminishing marginal utility of dollars exponentially, meaning a 10% raise yields the same happiness increase regardless of income level. While dollars have declining utility, real-world incomes, varying exponentially, offset this. Trade-offs benefiting lower-income individuals have exponentially larger effects on collective happiness, highlighting a tension between individual and collective happiness geometry.

This divergence may explain income inequality, income distribution shapes, and stagnant U.S. happiness. Unlike decision utility, which can be inconsistent as shown by Kahneman and Tversky with Prospect Theory, experienced utility, or actual happiness, appears to scale logarithmically with income. This suggests that while the marginal value of money declines, richer individuals are generally happier, with this trend extending beyond the previously thought $75,000/y satiation point.