The famous plateau was a measurement artefact; for most people, well-being keeps rising with income.
What the evidence shows
The '$75,000' figure comes from Kahneman & Deaton (2010), who found that day-to-day emotional well-being stopped rising with income around that level, even though life satisfaction kept climbing. It became one of psychology's most quoted numbers.
Using real-time experience sampling from tens of thousands of people, Killingsworth (2021) found no such plateau: experienced well-being rose steadily with log income. Rather than fight in the press, the two camps ran an adversarial collaboration (Killingsworth, Kahneman & Mellers, 2023) and reconciled the conflict: for the large majority, happiness keeps rising with income; a plateau appears only among an already-unhappy minority. The clean 'happiness stops at $75k' claim is best regarded as refuted.
Sources
Kahneman, D., & Deaton, A. (2010). High income improves evaluation of life but not emotional well-being.
Proceedings of the National Academy of Sciences, 107(38), 16489–16493
Emotional well-being rose with income but appeared to level off around $75,000/year, while life evaluation kept rising.
DOI: 10.1073/pnas.1011492107 →Killingsworth, M. A. (2021). Experienced well-being rises with income, even above $75,000 per year.
Proceedings of the National Academy of Sciences, 118(4), e2016976118
With real-time experience sampling, both experienced and evaluative well-being rose linearly with log income, with no plateau at $75,000.
DOI: 10.1073/pnas.2016976118 →Killingsworth, M. A., Kahneman, D., & Mellers, B. (2023). Income and emotional well-being: A conflict resolved.
Proceedings of the National Academy of Sciences, 120(10), e2208661120
An adversarial collaboration found happiness keeps rising with income for most people; a plateau exists only for an unhappy minority.
DOI: 10.1073/pnas.2208661120 →