20% tax on wealth (aka the potentially liquidatable value of an asset) would absolutely destroy anyone using an asset. For a classic example, look at property taxes which are a classic wealth tax. Grandma’s, people on pensions, and even middle class folks who own a home but have relatively low rates of salary increases get destroyed (and have to sell and move out) in places like Texas where property taxes aren’t capped/controlled like California under prop 13 when property prices go up.
Having your house get ‘too expensive to live in’, in fact, is a classic issue with property taxes, and was happening in California - which is exactly why prop 13 happened. And most of those locations the maximum tax is around 1-3%!
‘Wealth’ is not the same as income, because wealth is potential money, if you can sell - and if you sell, you lose access to it.
A 20% wealth tax would mean any asset which doesn’t earning free cash flow returns of at least 20% a year, or which isn’t appreciating at least 20% a year in a risk free way would be impossible to hold for anyone except the most rich people. And even they couldn’t do it for long.
I can’t think of anything which that realistically describes.
A 20% income tax reduces actual cash in hand to 80% of what you’d otherwise have, which isn’t great. But you still get the actual 80% cash in hand right now, and can use it.
You can’t have ‘80% control/ownership for the year’ of a house in a meaningful way, and especially for people actually using/relying on the asset to live, they can’t find 20% (or in most cases even 5%!) of the value in cash for the asset every year. They’d go bankrupt.