Well combining Keynes' thoughts about the 15 hour work week and the ideas in BS jobs, in a way Keynes was right. Most of the professional jobs that are high paying could easily be reduced to 20-30 hours per week with no productivity change. We aren't working 40 hours for more money, it's because we have a twisted work culture that continues to believe that more hours means more output no matter how long.
But also, I think Mustachianism is proof that there is no trade-off between 40's level standard of living and less work. We are proving that you can have both. This wasn't a trade-off society deliberately made. It's all about our culture
I think it's about the "blueprint for life" combined with factors beyond your control, along with lack of conscious choices on most people's parts saddled additionally with poor impulse control.
The blueprint is like this: Go to elementary school, junior high, then high school. Do good in high school so you can get into a good uni. Don't worry about the cost or what your taking, the most important thing is go to a good school and study what you love. It will be worth it. You do because that's what people do.
Then graduate with debt. Throw out 25 resumes. Work for who ever is willing to hire you and give you the most money. They dictate both the hours and how you spend your day. Buy a home on credit because that's what you do. The biggest you can. Buy a car on credit. The nicest you can. Because that's what people do.
Sock money away for retirement. Spend the rest on toys. Pop out 2.3 kids, put them in day care. More expenses. All the while spending everything you have extra on trips and TVs while patting yourself on the back for saving 8% of you're income. Retire at 65 reasonably comfortably. Because that's what people do.
I have several friends who fall picturesquely into this mold. And they by all measures are above average and successful. The common theme however is a lack of control or conscious choice. Literally flowing with the river, and picking choices that other people lay before you. You work 40 hours a week and buy the fancy car,
because that's what people do. Insinuating I would want to work 15 hours a week, or saying I haven't worked in over a year, or saying that I'm not concerned about maximizing my engineering degree for as much $ as possible, and I come off as a straight up weirdo. Social pressure is an incredibly strong force.