[NovemberWhiskey]

That's a nice theory at steady-state, but how do you get there?

If UBI is less generous than Social Security, then you have a problem.

You have lots of retirees (15% of the population) who have been promised Social Security and have retired on that basis. You also have lots of people that are relatively near retirement that will be in the streets with pitchforks if you threaten their benefits: Social Security is the original third rail of American politics - touch it and you die.

You basically need to allow people to choose whether to get UBI or stay in Social Security. This creates a gigantic fiscal bulge because you end up funding Social Security for everyone for whom it represents a better deal.

If UBI is more generous than Social Security, then you also have a problem. You are effectively exchanging it like-for-like and there's no extra tax take to spread around.