It removes a shit load of misc. other benefits and all the bureaucracy needed to maintain them. That might not cancel out but it's not purely extra costs.

Those other benefits combined don't come remotely close to $4T. I'd be curious to see which benefits you think could be eliminated or cut back and how much that would save.

The logic of it is that you could increase taxes to pay for it and above a certain income level, 100% (or more) of it would be clawed back in taxes.

The required tax rates would still be unbelievably high though. Way higher than any other developed nation (some of whom already have >50% tax rates).

Canada has a tax rate that tops out at 50% (mostly), the US caps out at 37%[1]. I think we'd all be better off if the tax brackets went a lot higher. Rich folks tend to have a lot of inactive money that's just sitting around doing nothing - we can put it to more productive uses.

1. Please note, these numbers are off of raw income tax - both Canada and the US have other employment related taxes that I'm not counting here (like payroll) since their proportional contribution is pretty minimal.

You aren't including state taxes.

I am for the Canadian ones - where I can easily count the provinces. I am indeed too lazy to do the math on how much each of the fifty states leverage in taxes but it looks like they tend to come out well below 50% (except for CA, which is fair). Specifically, CT caps out at 43%, NY is at 45%, CA is at 49% and TX is 37% - since there are 0% state income states I find it reasonable to assume that rich people concerned with income taxes will chose to live in one of those 0% income tax states.

and payroll taxes of 12% on first $140k.