Because you don't get to retire at 40 by working full time, and it's not even necessarily a good thing to be retired that early in life: cognitive decline sets

Because you don't get to retire at 40 by working full time, and it's not even necessarily a good thing to be retired that early in life: cognitive decline sets in, skills atrophy, you just generally feel worthless. I know because I usually take a year off between major job changes. After about 6 months it's pretty clear it's too early for me to retire. For most of us peak earning power only _begins_ in our 40s. So what you're actually proposing is that people spend a quarter of their life (arguably the _best_ quarter) working 60 hour weeks for peanuts to make somebody else (and that someone is likely working part time) rich, and "retire" with insufficient funds as a burned out husk of their former self.