re: #28 sagehen

and if somebody’s net worth consists mostly of stock in a company they control, do you force them to sell enough they might no longer be in control?

That’s a fair concern, though I’m not aware of any major publicly traded companies where someone owns an outright majority of shares. In such an edge case where paying 2% of one’s net worth would cause one to lose control of a company, a few options are readily apparent:
1) pay a dividend to pay for the wealth tax
2) take out a loan against a portion of the shares
3) issue a different class of shares with different voting rights.

I’m sure that there are other solutions.