Sometimes I wish I could have 10 million dollars. Then I'd be happy. According to this link, as one earns over $40k a year, the utility of each dollar earned decreases. This is the rational for our ability-to pay-tax philosophy. Taxing those with a lower value of money doesn't reduce happiness.
A man was in court for failure to pay his fair share of income tax. The man protested giving a long winded rebuttal. The judge found the man guilty and sentenced him to community service working the poor. The judge defended his decision saying that the man taxed his patience.