Figure in savings in the criminal justice and healthcare systems, and those 3 trillion are a real steal. From a real-world experiment:
Mothers with newborns stopped working because they wanted to stay at home longer with their babies, and teenagers worked less because they weren't under as much pressure to support their families, which resulted in more teenagers graduating. In addition, those who continued to work were given more opportunities to choose what type of work they did. Forget found that in the period that Mincome was administered, hospital visits dropped 8.5 percent, with fewer incidents of work-related injuries, and fewer emergency room visits from accidents and injuries. Additionally, the period saw a reduction in rates of psychiatric hospitalization, and in the number of mental illness-related consultations with health professionals.
Savings in decreased hospitalisation and prison time alone should be substantial. UBI done right goes way beyond a monthly payment.