Where does the UBI money come from? Even if it was only $10,000/year, that would be... $3.2 trillion a year.
How much do we spend now? Social Security + Unemployment Insurance + Disability + Food Stamps + etc. is $2 Trillion a year. By replacing/combining these into UBI, plus any savings from reduced administrative overhead covers most of it. (since there is no means testing, everyone gets a payment, resulting in a lot less administrative overhead.)
The rest is covered by a progressive UBI tax. People earning only UBI pay no UBI tax. People earning an average income pay as much UBI tax as they are getting in UBI. People earning above average income pay more in UBI tax than they are receiving in UBI.
I'm not convinced that it is a good idea... the devil is in the details, and no detailed plan has been put forth to be evaluated, but the basic concept is sound.