Adjust down to 10k-15k; the wage doesn't have to be livable in a single apt with no partners, but it should be enough that you can split out living expenses in a cheap midwestern city with 2-3 roommates. Welcome side effect, we spread people and wealth more evenly across the country in a small way. People are encouraged to find the cheapest possible living arrangements, which will include developing currently unwanted land.

Recognize that most people are going to be put off from the bare minimum arrangement, and that you don't have to pay people making above some arbitrary line, something like 6-7x the UBI.

Many of the social programs currently running could be shut down with UBI.

And all of these are based on the assumption that automation will continue to increase efficiency. Right now, it would be nearly impossible, especially with the legislation that exists. It's dependent on taxing the owners of businesses with high automation, recognizing that we're not far out from some truly massive automated systems, the most immediate being logistics and transport.