Or perhaps UBI can set people free to live as they see fit, cultivate themselves spiritually, artistically, and communally without needing to consume nearly as useless garbage.
Maybe! Or maybe it creates an enormous, permanent underclass living hand to mouth on what are effectively ration cards, lacking even the power to deny the machine their labor. Then, is that actually as bad as it sounds? A walk around LA's skid row is a strong case it's not. For me, it's eyebrow raising that a lot of the momentum behind UBI seems (anecdotally) to come from people who don't expect to have to rely on it.
It's clear that if automation continues apace something will have to give. UBI might be the answer, but I suspect it's actually not radical enough: that trying to bring money with us into a post scarcity economy is not going to go the way we want, no matter how good our intentions.
There's no such thing as post-scarcity. Scarcity is imposed by physics, not a lack of technology.
What changes is our expectations, beyond basic survival. Most people living below the federal poverty line have one or more televisions with active cable, a smartphone, and air conditioning; nearly all of them, in the high 99.x percents, have refrigerators, which implies that nearly all of them are housed as well, and effectively none go without food and sufficient warmth to sleep by circumstance.
In the sense of survival, the United States is effectively post-scarcity. What you're talking about is more "post-ambition".
Scarce is the opposite of proximate, not the opposite of plentiful.
Yes, we're nowhere close to "post-scarcity" in the Star Trek or Iain Banks sense. But proximity is also a function of technology, and in a hypothetical world where human labor is mostly obsolete (STEM included), it approaches zero.
It's fair (and I think correct) to not expect the world to go so far in that direction any time soon enough to be relevant, but many do. Scratch a UBI supporter and you'll often find a big believer in AI.