Nobody making under 250k would be paying into it and unrealized gains would be included in figuring all personal income. The ultra rich are paid mostly in services like corporate jets, meals, stocks and options. Salary is pretty minimal compared to all the other perquisites that come with SVP/Director on up to the c-suite level jobs in the top 1000 US companies.
If I made 350k all in and UBI takes 35k, I still take home 315k.
Heck, that portion of income that goes to UBI doesn't even have to count toward regular income taxes. It can be all pre-tax dollars.
The thing is, the economy works best when everyone can participate fully. Locking huge swaths of it into personal fortunes nobody could hope to ever spend in a lifetime is wasteful and puts a huge drag on the overall economy. Sure, they can pop for houses and planes and yachts but that doesn't really come close to the kind of economic power generated by millions of working poor buying their daily essentials.
Link your end with the start. The top earners don't have the income to finance it.
My point is not that UBI should be a tax on the rich but that regular citizens can finance it right now if they want it.
You hope that UBI comes for free. It won't. The majority has to pay it with higher taxes, voluntarily or not. So if they want it then don't wait for politicians but implement it right now.
Zakat? It's only 2.5% (can be up to 20% depending on what school of thought you follow) and it's not distributed to everyone. There's only a subset of people who are eligible in receiving zakat so it's not UBI.
Although there can be a lot of things that can make someone require to pay zakat, like income, wealth, business assets, and others.
OK, total personal income for the US is 21 trillion so you've raised $2.1t. 260 million adults. That's about $8000 each. Can you live off that? I'm not sure I could and I own my home outright.
When they live off, I think they mean is that enough to where you could live on that and not work. And the answer to that is no/not well in the majority of cases.
The point of UBI is that you could just live off that if you were frugal.
Everybody gets it of course, but you'd lose 10% of your current wages too. Everyone under $80k would be better off, everyone over that would be worse off.
The thing with UBI is that you'd lose all other state benefits too. Pretty much anything means tested would go and be replaced with one payment that everyone gets.
If you look outside the US, you can get housing for a price that leaves enough of the 4000 for other expenses.
The easiest option is to connect some barren land to a city center with public transport in a climate zone that doesn't need much insulation. But that just as a proof of concept. More clever options can be realized.