$10,000 * US_POPULATION ~= $3.2T ~= The total annual tax revenue of the US federal government. Just something to keep in mind when discussing this topic.
Don't have an opinion on any of this, but how many of the population you calculate are citizens over the age of 18? And what would be saved from the US budget by eliminating various existing programs that would be superfluous by UBI?
Is there a risk here that the more vulnerable members of society will end up receiving less money?