The federal deficit is 2.8T for 1 year.
If we confiscated the 100% assets of the top 10 US billionaires we don't even get close to half of 1 year of federal spending. It's not plausible that a massive increase in taxes would pay for UBI.
https://www.statista.com/statistics/201426/the-richest-peopl...
As is, people not participating in the workforce right now is implicated in large parts of the various shortages. It's not clear how UBI improves things.