The idea of a "one time" tax is so stupid that any person, regardless of income, should oppose it. It just makes no sense whatsoever.
There's one use where it makes a lot of sense though: massive downpayments of government debt. Though it should be paired with an iron-clad obligation (like a constitutional amendment) not to let the debt rise like that again in the future.
Well the government goons will get into debt even if you pay it. They love money printer.
One time wealth tax on unrealized gains in a state that has already high taxes is weird.