All of the wealth has been taxed before, often multiple times. Adding another layer sure seems like overkill.

The wealth has barely been taxed at all. Wealth comes from holding assets not from labor, and asset ownership is barely taxed:

1. stocks and commercial real estate are allowed to appreciate without taxation (unlike personal residences outside Cali),

2. multinationals wrote for themselves obscure tax rules so they end up paying almost no tax,

3. interest expense for companies and ultra high net worth individuals is subtracted from taxable income (for personal mortgages the interest expense deduction is capped)

4. Rich people organize their assets so estate taxes do not tax their estates when they die and thus their wealth goes to their children.

As you can see wealth is barely taxed.

Well, no, it hasn't. Much of the wealth is in the form of unrealized capital gains. It won't be taxed until it becomes a realized capital gain, that is, until the underlying asset is sold.

Um no.

"The income tax base captures 60 % of economic income of the top 1 % of wealth-holders."

https://www.sciencedirect.com/science/article/abs/pii/S00472...