"Money doesn't bring happiness" is upper class shorthand for "incomes above six figures in the US don't provide significant marginal benefits in terms of person

"Money doesn't bring happiness" is upper class shorthand for "incomes above six figures in the US don't provide significant marginal benefits in terms of personal satisfaction and overall happiness". Money is obviously pretty great to have. The point of the cliche is to caution people about making too many sacrifices to chase millions.