I share those same thoughts/questions.

Even if the cost thing is figured out, UBI has other issues. If it's truly universal, recipents will be priced out of just about everything that involves competition, including housing. If it's needs based, it's hard to determine the proper recipients. This may also lead to underutilization of talent when the benefits are close enough to what a person who could get a job would end up receiving. It would be nice to see some large scale tests, but that still hasn't happened.