UBI is a fantasy. Capitalism is the one system that has consistently worked to raise people out of poverty.
Capitalism has never raised anyone out of poverty without controls on who can profit. As we have weakened those controls, capitalism has become less of a force for lifting people from poverty and more of a force for keeping them there.
UBI isn't anti-capitalistic any more than taxation. Both are ways to make the system work sustainably.
People are not going to be out of work. Old jobs may disappear, but new ones will appear.
That is not a cleanly managed process with working social systems to handle the overlap. The social safety net payout amounts are all based on a federal minimum wage which is not sufficient to maintain a reasonable standard of living in any state. Some of the numbers we still use today to determine eligibility, benefit amount, share of cost etc. are from the eighties, while others are from the sixties.
Each major disruption has improved life, and AI will be no different.
Each major disruption has literally caused people to die because there has not been enough management of the transition. If you say that AI will be no different, and you also say that the change should be celebrated, then you're saying we should celebrate negative effects up to and including deaths.