In 2018, Harvard Business School undertook a first-of-it's-kind study of over 4000 millionaires in the United States asking them about how much money it would take to make them happy. Each millionaire was asked to report how much they currently had. How happy they were on a scale of 1-10. And then how much money they thought they would need to get to a "10" on the happiness scale. Shockingly, 26%, the largest response was assigned to "10x more," the largest possible option given. 24% chose "5x more" followed by 23% at "2x mores." Only 13% of respondents said they "currently have enough to be happy."

Perhaps most surprising of all, this answer was consistent no matter how much money a person had. This means that someone with 100 million was just as likely as the person with 10 million to select they needed "10x" the amount of money they had to be truly happy. In an interview with The Atlantic, lead researcher Michael Norton suggested that the problem for so many millionaires is comparison. So the question of happiness is not so much "Do I have enough?" but "Do I have more than those around me?"

Norton concluded, "If a family amasses $50 million dollars but moves into a neighborhood where everyone has more money, they still won't be happy. All the way up the spectrum of wealth, basically everyone says [they’d need] two or three times as much to be perfectly happy."

Source:

Grant Edward Donnelly, Tianyi Zheng, Emily Haisley, and Michael I. Norton. "The Amount and Source of Millionaires' Wealth (Moderately) Predicts Their Happiness." Personality and Social Psychology Bulletin 44, no. 5 (May 2018), pages 684–699. Joe Pinsker, "The Reason Many Ultrarich People Aren’t Satisfied With Their Wealth," The Atlantic (12-4-18)