Wealth taxes are horrible because they'd require doing a balance sheet to determine all your assets. Things like pricing all your collectibles accurately or determining the present market value of art pieces is a huge pain in the ass. It's also really nasty having fines if the government disagrees on your assessment of values. You'd have issues like the government suing people over mispricing the pokemon cards shut away in their basement where 1st edition charizards are now worth $55,000. Doing a balance sheet every year for taxes really sucks. Income is much simpler to calculate and adjust. It might make sense for wealth above a huge magnitude but at that point it becomes a very small % of government revenue and not something that replaces income tax or truly affects the balance between capital and labour.

There are also nasty effects with start-ups stocks or options that may be worth quite a lot of money but you may not be permitted or be heavily restricted in selling the stock even if you execute the options. There may still be a possibility of the stock going to zero leaving you with a large tax bill and no value in assets.