I don’t need an income but I do need a job. My art is my work and my work is my social life. I tried retiring and it was not good for me, all my friends were busy working doing the good things I did when I was working. When a coworker asked me to come work with him at his new company I quit retirement and am helping him grow his company. I have learned more by working than I learned in 17 years of formal education.
21 hour work week means I could work two jobs and have even more coworkers.
What about the self-employed, do you expect them to limit themselves to 21 hours of work each week? If my wife and I were running a bait shop, I guess you think we should hire someone else so we don’t have to work more than 21 hours a week. Silly, then we would not get to talk so much with our friends/customers. I would not be hiring help to reduce my work hours so much as to groom someone to take over the business so our friends/customers would continue to get quality friendly service should something happen to us. (if bait bothers you, you can replace bait with bagel, same deal.)