UBI wipes out all the bureaucracy, humiliation, disincentive, stigma, and time-wasting that come with the means-tested types of programs it could replace in the real world (food stamps, housing vouchers, unemployment, etc)
So you are suggesting that when people blow their UBI on drugs, fast food and high rents, they are shit out of luck?
There is nothing rational about this break down. You are using current cost savings to reduce the total cost of an imaginary program. Its absurd.