Very helpful and informative. I'd made that same mistake myself - although I knew about the savings from replacing expensive means tested social-welfare programs plus the increased incentive to get a job because no UBI is lost.
But Americans (I know we are not the only ones who could benefit - pretty much every country could) are terrible about anything like this. You could explain this to them a dozen different ways and a dozen times and they would not get it. Sigh.
Even with widespread and highly successful rollout of UBI in nations across the world they would still say "tax is theft!" and leave it at that. Never mind if it was costing more to administer the alternative and not including the missed gains for a more equitable wealth distribution. This is exactly the same as single-payer healthcare...doesn't matter if it costs less, works better and is fairer - don't want that, smells like socialism!
Anyway, thanks for a more objective run down of the concept than I can manage :-) Have you seen any actual scenarios examined for the US based on our actual income and tax system?