> What made me change my mind about UBI was to realize that a) human desires are infinite, and there'll always be more work to be done and b) the more work is done by machines, the richer the population as a whole will be, as products and services automated tend to be cheaper.

I agree with this sentiment. Looking into the (very long term) future, it's interesting to look at a fictional post-scarcity society (Star Trek) (with a grain of salt - it's really the writer's imaginations and what you see in the movies/shows) and see what the impact would be. My key takeaways are:

* everyone still works, or studies, and the culture is that you still contribute to society rather than sit around and do nothing. This requires a significant culture change from our current society.

* They often visit colonies and planets that are decidedly not post-scarcity - they are often poor or middle-class colonies, with an agricultural bent. In theory this shouldn't be the case in a post-scarcity society, but it becomes apparent that there's still a cost (resources and time) associated with production and transport unless you want to be ruled by AI overlords.