I have understood Musk's speech in another way. "Work is optional" would not mean that all work was optional. It would mean that the AI productivity boost would lead to enough wealth to ensure a basic lifestyle for everybody (note the word "basic" in UBI). In this world, there would be still "money" and also incentives to get something better than the "basic level".
In reality this would be only a gradual change from today's "welfare state".
I don't think Musk was trying to say this (I think what he actually said was utter gibberish), but I agree with that future prediction, presuming everything else goes in that direction (see below).
Also such an abundance world could lead to more risk tolerance if you never have to fear to lose "everything". Maybe even "speculative" goods like Bitcoin would be the ones most benefitting from such an outlook.
I agree with this. In the US, Obamacare made it so people could quit their jobs and not worry about losing their health care when they moved to a new job. That made it so people could switch jobs much more, which allowed them to take more risks.
A stronger safety net (not UBI, but a more advanced and comfortable "free tier") would increase that factor even more. People would know that they could go absolutely broke, and still be "okay"--not desirable, but not terrible either. Hence you will have a lot more people "going for broke", which will probably produce a lot more innovation in our society (but a lot more gambling, too).
I think this theory for sure has some merit and in general I would agree from a first glance with its basic premises (as long as the average education level doesn't decline), but I wonder if there isn't a ceiling for the "superabundance" concept, i.e. if there can be a saturation of inventions, a bit similar to the concept of marginal utility. Does he explore that idea in the book? If yes then it might be interesting for me.
Humans strive for things that are rare. Whatever is "superabundant" is by definition not rare. Hence if there are robots spitting out Ferraris by the thousands and anybody can have one for free, then people won't like them anymore (they will covet the old, "hand built" cars that were objectively inferior by every metric however).
AI slop, as it's being called, can apply to everything, including things that keep you alive such as a robot-built house or robot-built food. And it will be "okay", but it will never be "great". People will still want "hand built" (using that idea very abstractly) things and they will pay for them if they have the means, which they will if they are lucky and/or work hard and/or are uniquely talented.
In other words, the basic structure of society won't change (rich people, poor people, etc.).
And obviously there will still be money. And yes, speculative things like Bitcoin will have a lot more buyers in that universe as well.
You can already see this in metrics today. Crypto buyers weigh very heavily to younger males--people with less to lose, and no family to worry about if they go broke. That effect will get more pronounced if, say, you can have a viable family life without having an income--then
everybody can be crypto bros

.