There is a very real logistical problem with directly taxing net worth. It's extremely difficult to actually assess, especially when you're targeting people with extremely expensive lawyers. They also very directly encourage wealth flight, which has happened in other countries that have tried them. They can also be avoided by accounting trickery, shell companies, and all kinds of bullshit. It's not me that owns $1 billion in Amazon stock, it's a shell company in the Cayman Islands that happened to buy a yacht. Sure, you can unwind all that, but enforcement takes a lot of time and resources.
There are other much more efficient tax schemes out there focusing on consumption that can't be easily escaped.