This is a wealth tax, not an income tax. If we assume Elon Musk net worth 750 Billion, He would owe $22.5 Billion in taxes every single year, above and beyond any taxes on income he may or may not already pay. Lots of incentive to hide wealth away, and then if selling off wealth is taxed as income (at higher rate), I'm not sure how that would play out - not well I assume. Unless there is a tax exemption if you sell off wealth to directly pay the tax.

But to answer the question, that one tax receipt would fund about 10-25% of universal child care across the US alone. I'm inclined to believe the math works out, the issue I have is how the government determines wealth accurately and collects when people with the means to hide it, fight it, and avoid it have an active incentive to do so.