Current "work for a living" systems only sustained the population because a human could be the most cost-effective way to get something done. Unless there are still tasks where human labor is the best option (research jobs maybe), this entire economic system will collapse.
But where will they make their billions from if everyone will be living on a basic income? Less money for them will mean less tax money, and less UBI. It will spiral out of control into complete societal collapse if AI doesn't hit a plateau soon.
That is why I said "solid UBI", as in more than merely survival wages, i.e., enough to not merely buy food & shelter, but also to live.
That said, this does need some thinking through multiple stages. On one hand, societies did still work when there was effectively unlimited slave labor, but that may be no more than a rough proxy.
Go to the endpoint assumption that AI and robots can produce everything needed for the population to live, and they are owned by 1% of the population. They made so much money so fast that they bought all the means of production. As of 01-January-2025 everyone is fired. Now what? Your'e right, no one can buy anything. The remaining populace cannot do anything because the new oligarchs have enough money and power to buy &/or threaten any politician.
The population overall is not going to simply lie down and die. About four days after running our of all the food in their pantries, they'll be revolting in the streets. One plausible result is a lot of carnage and the oligarchs are all killed and the AI is destroyed and outlawed. Or, they actually have sufficient command of the military and no defections and the military isn't smart enough to figure out that they're next on the starvation list, so the populace is wiped out as they revolt, and the world is left with the 1% of owners, and 1% of military. Or, there's some kind of balance reached, and the non-AI-owning class of fired people reconstitutes something similar to last year's economy, while the 1% go off to Mars or withdraw into their metaverse-ish thing.
That's just a few random thoughts on rolling the dice among the big forces, but it never plays out like that, so all of these are 99%+ likely to be wrong.
Seems like the only thing we know is that this potentially massively magnifies instability.
This is part of what the original UBI concept was about.
If this doesn't happen, yes, there will likely be violence until it is fixed.
The other view is that many technologies that were supposed to reduce work actually net added work, because now more sophisticated tasks could be done by the humans, so the net was similar to the highway paradox where more and wider highways breed more traffic by induced demand.
Where would this demand come from? IDK, but at least initially, these LLMs make such massive errors that keeping a lid on the now-hyper-industrial-scale bullshit[0] spewed by these machines will make many more full time jobs.
Seriously, just today I was amazed at how the GPT model tried to not only BS me with completely fabricated author names for an article that I had it summarize, but it repeatedly did so even after being successively prompted more and more specifically to where it could find the actual author (hint: right after the byline starting with the word "Author". It just keep apologizing and then doubling down on more fantastic lies, as if it were very motivated to hide the truth (I know it's not, that's just how fantablous it was).
[0] Bullshit being defined as speech or writing telling a good tale but with zero regard to the truth or falsehood of any part of it — with no malice but nonetheless a salad of truth and lies.