Okay, suppose your income is proportional to your working hours. Work 40 hours, get 40. Work 60 hours, get 60. Would you rather work 20 more hours a week to have 50% more money? I wouldn't. It's true you need money to live, but I don't have a terribly expensive lifestyle, and I would rather keep the free time I have now than work more and have more money. Time is more valuable.