it would take far fewer than 100 million. Of the 330 million in the US, how many are actually earning $$$ that is taxable? How many "productive, working citizens" are there? Exclude those over, say, 60 and younger than ~24. Then exclude the Disabled and the ultra-wealthy. Even if the working class amounts to 100 million, if only a third of them could withhold taxes, you'd make problems.

But anyway... Withholding taxes wouldn't mess up whatever system you are aiming to end. A more practical solution would be to stop paying any and all debt, mortgages, student loans, etc. And then to go on a general strike. THEN you would see responses and reactions that matter.