Generally speaking, the total output value of the national economy is positively correlated with the sense of happiness. The more the per capita income, the happier people are. However, when the total output value per capita exceeds 8,000 US dollars, the correlation between the feeling of happiness and the economy is not obvious. According to the famous psychology According to Seligman's point of view, wealth only has a great impact on happiness when it is lacking. A particularly poor person will not feel happiness, but when wealth increases to a certain level, the correlation between wealth and happiness will be much smaller. Even among the top 100 in the Forbes list, with a worth of 125 million, they are only slightly happier than middle-income people. The text is intended to explain:. ['There can be no happiness without wealth.', 'Wealth and happiness are directly proportional.', 'The more wealth there is, the less it is related to happiness.', 'Billionaires are no happier than the middle class.']