Ok, and on the 2nd the price crashes, company goes bankrupt, stock is worth zero. You were taxes on theoretical value that you can't sell at to pay that tax.
For me, a lot of these issues become immaterial if the threshold is high enough. If the threshold for a particular tax is assets over $100 million, or a billion, then the answer can just be "you are totally screwed" and I'm basically fine with that. If you don't want that risk, just don't get that rich.
