and #3 at least as already been well modelled economically, UBI replaces many other welfare programs, so we can definitely afford it
As GGP said, this doesn't compare. There's even nothing magically non-linear about it: people stay employed, because they know the UBI study will only last a few years, after which they'll need to get back to normal. It makes no sense to interrupt your career for it, as the "hole in your CV" will just turn into a severe and compounding disadvantage in lost years and experience.
The only way I see this being sustainable is get as far as possible from the big cities, buy a tiny piece of land, by a durable tiny home, buy solar panels, get a tablet with all Gutenberg books, and find a soulmate that will follow you to that journey.
No kids, no private schools, no parties, no nothing. Everything will be swallowed by inflation.
I believe this to be a fundamental feature of free market economy in general. It's something I started realizing many years ago, and thought about a lot ever since; in the last year, I distilled that belief into a concise phrase I now use for this:
The market constantly adjusts to keep the average disposable income to zero.
Except now I realized that "average" is the wrong measure here, I should be saying "median", and also I've been mistakenly using the term "disposable income" (which actually means just after-tax income) to refer to "discretionary income" (what you're left with after covering taxes, bills, and essentials). Which leads me to the New and Better, Updated, Version 2.0 of my economic theory:
The market constantly adjusts to keep median discretionary income near zero.
I'd imagine this is an obvious thing that's already been named 100 years ago, but so far my research only pointed me to things like "neutrality of money", and some specific examples of my statement holding, yet nothing that covers it entirely.
(EDIT: in the unlikely case I'm not an idiot, and that this phrasing was not used/named before, I welcome credit; inquiries from the Nobel Foundation should be directed to my e-mail address, which is in my profile.)
Oh yes!! This very thing!! A quick DDG search didn't return anything, but yes, 300% yes. This is the rule/law. Once people get some money, forces tend to (try and) take it away.
EDIT: Ideally, your disposable income must be a little less than zero, so your needs/wants outpace your income, so you get a credit card with $2k limit, then you expand that to $5k limit, and that to $7k limit, until you cannot any more.
EDIT2: I once dated a lady (the most beautiful woman I've dated in my life) and she was in debt for €40k, ALL spent in clothes. She was SO gorgeous that when I feel for her she was wearing a €50 jeans and a €10 white tshirt. She walked in to the room and people stopped breathing. After 1.5 years of dating when I wanted to get very serious with her and she told me her 'dark secret', I suggested a Dave-Ramsey-baby-steps plan to pay off her €40k debt but to chop up her credit cards (and I would gladly generously contribute to pay off that debt - but with a different lifestyle). Long story short.. I haven't seen her in ~15 years :)
In general, as long as we're funding it with taxes instead of by printing money, it's not going to cause any extra inflation.
That's almost twice the aged pension here in Australia. (550 GBP)
I guess I would also need some iron clad guarantee that the cost of living would not skyrocket.