My house isn't very liquid, can't generate revenue very effectively, and I'm taxed every year on its current value. Guess us regular folks are already subject to a wealth tax.
And yes, all the reasons why "taxing X would actually be harmful for the economy" somehow magically do not apply to the small fish.
If you want to say it's difficult to tax illiquid assets, that's fine. But it's not impossible and while it would just change people's relationships to these types of assets (maybe in a good way for society), it's not going to be the end of the world.