The point is that the rich people who ultimately pay for UBI (and for the lobbyists), will want to eliminate as many people as possible and reduce the amount given.
There are nowhere’s near enough rich people to fund UBI.
For every 5% you raise income taxes on the 1%, you get about 65B additional taken in by the Treasury. PER YEAR. So, you fund even that rudimentary 326B figure you allude to (one can hear the screaming now that 1K is not nearly enough) per MONTH, you’d have to raise the rate on the rich more than 25%, which is an amount that no economist outside of an insane asylum thinks is sustainable. PER MONTH.
Reality? If you want bells and whistles like UBI, that money is coming from a doubling, and perhaps tripling, of the tax rate on the middle class and up.