Roughly 19% of the US population is on disability or social security retirement benefits. 23% are under the age of 18. 38% are employed full-time. Disability/S

Roughly 19% of the US population is on disability or social security retirement benefits. 23% are under the age of 18. 38% are employed full-time. Disability/SS is a straight-up income replacement. They go off one program and onto another. People under the age of 18 are much cheaper to support and would get somewhere between "much less" and zero dollars. Full-time employees basically get an accounting trick - on average, taxes go up by roughly the amount they receive in benefits. This makes up a combined ~80% of the population, meaning there's a new benefit for roughly 20% of the population. This is about the same size as the current social security program. Difficulty of going from our current regime to UBI is roughly as difficult as setting up social security in the first place, so it's roughly the size of the New Deal. Difficult, but not impossible - something that you'd expect politicians to accomplish once every generation or three.