These studies don't really prove anything. Common arguments in favor of these studies - "They prove people don't quit work on UBI!" - No, they prove that people who are in a program that is very clearly temporary will not end their careers for a short pilot program. This means nothing. "They prove people won't spend it on drugs, booze, and lotto tickets!" - No. If you make $1k from a job and $1k from a pilot program…
I'm puzzled why we can't phase it in over time. Start with $100/month. The US can handle that. And then ramp it up as we see fit.
For example a government interested in reducing CO2 emissions could introduce a tax on motor fuel of say £1/litre and balance that with an increase of the basic income of £75/month.