We have any proof it works?!
Besides, I see two serious problems:
1) There's always the political incentive to raise it. More people benefit than are harmed, thus it will bring votes even as it crushes the economy.
2) It's a trap. You'll end up with the lower segment of the population not having useful job skills. If for whatever reason you have to scale back/eliminate UBI you have a bunch of people who are effectively non-workers.
I used to support it but I've come to realize it's not a solution.
There's also the approach of a negative income tax, but to be at a useful level this would push a form of graft--fake jobs with kickbacks. (I'll hire you to sit in the office for $5/hr. You pay me $8/hr under the table from the tax rebate you're getting.)
I also dislike approaches like universal health care--from looking at the nations that have implemented it it has a major fox-guarding-the-henhouse problem: the same people decide what the standards are and spend the money to meet the standards. Oops, the route to getting votes is to lower the standards as that gets you more votes from low taxes than loses from people lacking treatment, especially if their doctors never tell them of the problem. (You're not likely to miss option X if your doctor doesn't tell you about it in the first place.)
Something I would like to see is to modify the ACA towards lower copays and a much lower *monthly* out of pocket max (perhaps tied to last year's AGI), then give everyone a subsidy equal to the cheapest plan they qualify for with a forced-placement system to that plan if you don't pick one. And I would like to put a time limit on the wait for service--for a routine matter they have say 30 days to provide service (first available appointment with the proper type of doctor) or they have to cover out of network as if it was in network--and once that's been triggered you can keep that doc regardless. The clock starts on the day the referral is made, or the service requested if referrals are not required.