If you doubled ALL federal income taxes in the US, you could pay each adult US citizen ~$1500/mo in UBI.
And of course, the higher you set UBI, the less point there is to work like a chump and pay 2x current tax rates so other people don’t have to, so fewer people would work (which is one of the promises of promoters of UBI), meaning taxes would have more than double to make the payments.
The math is daunting because the number of people is so high.
A negative income tax is probably the best way to implement a UBI as it would require only distributing money to those that are below the income threshold, and it would prevent political opponents from trotting out big scary numbers on how much it would cost, while ignoring the necessary accounting required to truly estimate the financial impacts.
Thereby likely forcing those business owners to rely on UBI entirely for income, thus removing their upward mobility.
For example if you put $30T into UBI, and everyone saved it, you wouldn't have any inflation.