UBI is not a donation. It is forcibly taken at gunpoint (though they will ask nicely many times before pulling out the gun). Also, there can be no "unconditional" giving without "unconditional" taking in a world with finite resources.
As for UBI specifically...
> It is forcibly taken at gunpoint (though they will ask nicely many times before pulling out the gun).
This is the case with all taxes.
> Also, there can be no "unconditional" giving without "unconditional" taking in a world with finite resources.
This already happens all the time. The money for the military and Medicare has to come from somewhere, after all.