I'm of the mind that UBI might work with the absolute minimum of amounts. Give enough for food, a bus pass, renting a room (not an entire apartment), and some for incidentals. It would basically be "stay out of trouble" money, from which people can physically live, which allows them to then go forth and pursue something societally beneficial, because you don't just want to stay at that level. In theory, this might make their income less available to predatory targeting.

However, with a looming jobs crisis, the assumption of being able to go out to earn more remains to be seen.