UBI is not a good idea.
There is an old saying: "Idle hands are the devil's workshop." I don't know if that's one of the official Gods of the Copybook Headings, but it should be. Busy people, people with a job, don't have time to cause trouble. (Politicians and bureaucrats don't count there.) People who have nothing useful to do, will do SOMETHING. Some on the UBI will sit there watching TV. Some will be busily making more people to go on UBI. Some will discover an interest in painting and literature, or perhaps invention. And a lot of the rest will make trouble. Multi-generational welfare is not a pretty sight, and that is, at heart, what UBI would be.