It seems quite an assumption than grown human beings inherently require a supervisor "keeping them busy" for their quality of life.

It's true to a certain extent in current society (speaking from the US anyway) due to our relationship with work: one's job is seen as their value to society, while meanwhile it's very common (I daresay normal) for people to spend their time doing jobs they don't like and don't inherently care about, working just to keep employed. In such a system if someone no longer needs to work, they've "won" the rat race. They no longer have a debt to pay society and they can lie on the beach until they rot. I would not call this a healthy attitude, but it's my sense of how our society feels about work and "leisure". Other systems are possible.

Basic income is one way we could change the equilibrium; a BI high enough to provide a decent quality of life would alter our relationship with work in several ways:

- jobs no one wants to do would have to be made worthwhile. If people had the option of not working in Walmart, you'd have to pay them a whole lot more to keep doing so. On the other hand, you can attack it from the other side and make the low-skill jobs less soul-sucking: even mopping the floors in a huge supermarket wouldn't be so bad if say, the employees own the store, they know each other, and have a sense of community; they are not jumping through the require hoops to receive a paycheck but doing something that needs to be done for an organization that matters to them. I've met a lot of people who could be satisfied washing dishes their whole working lives, if they had a sense of financial security and employers that treated them respectfully. One thing these people have all had in common was they were involved in their workplace as a community. So I don't think unskilled labor is inherently abhorrent to the human psyche, I think a lot of people, given the choice not to, would still do jobs currently considered menial if the other things about doing that kind of work environment didn't suck.

- it tames the specter of Unemployment. To put this in a HN perspective, think of the holy grail for tech startups: Venture Capital. Speculative funding enables people to work on creating something, yet still be Employed while the project is not yet earning significant revenue. There's a cost of course: a lot of the project's profits go to rewarding people whose main role was having the money (and knowing what a potential good idea looks like, to be fair). It's a great system, it really is; what we've created in it is impressive. But I think BI would make things simpler for many startups; bootstrapping becomes potentially much easier than spending half your time chasing funding, when the members of the project already have a secure income and can focus on making something. Of course, it's much more general than tech startups; there are many things not being created (some of which could actually sell very well) because the would-be creators are "earning their livings" (what a concept!).

- more generally, it reduces the need for an employer. Businesses have been becoming increasing agile and fluid as employees become freelancers due to massively decreased friction in the business-to-business markets thanks to the ability to collaborate online, from anywhere in the world. The largest barrier remaining keeping many people from working for themselves is risk; an employer offers steady wages. Even if finding one's own contracts would pay more than doing the company work, volatility is rightfully frightening in our economy.

So yes, having a sense of purpose is very important. But the necessity that that purpose be "following the commands handed down from The Man" is only an artifact of traditional thinking about Life vs Work. I think we would tend to find more, not less, meaning in all the time we spend working under a BI system, since it gives people the power to do work they care about and employers the mandate to make their jobs jobs worth caring about.