...of our robot overlords taking more and more jobs away from us (More even than Mexicans, if you can believe it!). It's already happening is a very measurable way, and when AI becomes good enough to start putting meaningful numbers of white collar folks out of work as well, that's probably the event horizon.

UBI as general bootstrapping for poor folks, however, is not a good idea. We're still culturally wedded to the idea of the nobility of a day's work. Hell, half the country still thinks that a desk job isn't really work. Economically speaking, the only way it might even start to work is if it allowed to the elimination of a massive amount of social safety net overhead costs. But I doubt that's possible.