What happens if a large number of people can not afford a meaningfully better lifestyle than what is possible on a UBI because of the tax increases?
(Genuine question, no gotchas here)
(Genuine question, no gotchas here)
Or, maybe you're taking that into account already, and are worried about an uncanny valley in between "not working" and "working" where a significant number of people simply don't work because that first rung in the "working" ladder isn't rewarding enough to start climbing the ladder, so they're incentivized to never work. If so, that's certainly a concern, but that would also be an indicator of a failed system that needed to be revised. It goes without saying that any implementation of a UBI system would have to be designed such that that didn't happen, but that's not an intrinsic quality of UBI systems.
Tax increases themselves would have to be progressive (as our current tax system supposedly is and always has been) to avoid creating these sorts of discontinuities that would disincentivize people from working. Any functional UBI system would have to take that into account, otherwise it's a failed implementation.
This was a concern with the recent economic assistance bill, the additional money from this bill going to unemployment was higher than minimum wage. Should the amount given been lowered so that "it doesn't disincentive work"? Maybe this shows that minimum wage needs to be raised?
You seem to forget that while you might be an affluent middle/upper class person, a lot of people out there are struggling really hard to fulfill their primary needs. You realize how many people in the states are poor (lacking primary needs resources) or borderline poor? Yes, some people (plenty of HN users I am sure) might struggle to maintain highly consumerist lifestyles (not sure if that's necessarily bad) but for the majority of people, this will improve their lives for as long as UBI is a thing. All the money spent on fighting social phenomena that is the result of people being unable to or/and having being raised without enough primary need resources to ensure their physical, emotional and cognitive capabilities are not hampered by their poverty will be able to be allocated to better uses?