> What's stopping prices from rising accordingly?

Short answer: supply & demand

Long answer: if the supply of a thing isn't constrained (either naturally or artificially), then prices will rise in the near term, but will settle back down in the long term as production catches up with demand. This is why giving poor people food stamps (which is just food money) doesn't necessarily increase the price of food.

This mostly only breaks down in housing, for which there is a true supply scarcity — but even that ceases to be true in a regime with proper zoning reform. Even in regions without zoning reform, you now have people that have cash to move to cheaper neighborhoods — or even cities.

> How will the ~$3T yearly UBI bill be paid for?

Either progressive taxation, a VAT, or some combination thereof. I can try and give you a theoretical tax breakdown using real numbers.

In 2018, the household income quintiles were as follows[1]:

Lowest quintile mean: $13,775

Second quintile mean: $37,923

Third quintile mean: $63,572

Fourth quintile mean: $101,570

Highest quintile mean: $233,895

There were about 159M employed persons in the US in the most recent high[2], about 50% of the US population. We want our UBI to cover everybody.

To make this simple, because quintiles comprise an equally populated group of people, let's imagine that instead of there being ~32M people per quintile, that our nation has 10 people, where 5 people don't work, and each of the remaining 5 falls into one of the quintiles.

If we wanted to define a UBI of $18,000 per person, we need to somehow come up with $18,000 * 10 == $180,000 to distribute to everyone equally.

If we fund this progressively, each individual would have to pay:

Unemployed #1: 0

Unemployed #2: 0

Unemployed #3: 0

Unemployed #4: 0

Unemployed #5: 0

Lowest: $8,000

Second: $12,000

Third: $18,000

Fourth: $33,000

Highest: $103,000

Total revenue: $180,000

Then consider that everyone here is receiving back 18,000 under the UBI. The highest quintile earner’s net take-home is, thus 233,895-103,000+18,000 == $148,895, which effectively renders their net tax rate approx 36%. If you run this breakdown across all quintiles:

Unemployed #1-5: $0 - $0 + 18,000 == $18,000

Lowest: $13,775 - $8,000 + $18,000 == $23,775 (effective tax -73%)

Second: $37,923 - $12,000 + $18,000 == $43,923 (effective tax -16%)

Third: $63,572 - $18,000 + $18,000 == $63,572 (effective tax 0%)

Fourth: $101,570 - $33,000 + $18,000 == $86,570 (effective tax 15%)

Highest: $233,895 - $103,000 + $18,000 == $148,895 (effective tax 36%)

You'll notice that the top 2 pay a tax rate that’s comparable to today’s. We wouldn't necessarily need to increase everyone's taxes by the above amount, because there's some wiggle room in the Federal budget. Examples, we can probably eliminate Social Security (which would just be replaced by the UBI), Medicare (which is an in-kind donation that the UBI can be used to pay for), Medicaid (ditto), EITC/CTC (basically already a BI), and food stamps (ditto).

Also notice that because the lowest quintile still ends up with more than the unemployed person after their taxes, there isn’t a disincentive to work.

We can play with different levels of progressivity and generosity, but the idea is the same. We can scale up from single-person quintiles to million-person quintiles, but the percentages don't change.

[1] https://www.taxpolicycenter.org/statistics/household-income-...

[2] https://tradingeconomics.com/united-states/employed-persons