It’s hard problem that can only be solved through attempts and iteration. The fact that a wealth tax is difficult is not a good enough reason to not try, because the problem of wealth inequality is so severe now.
There is lots of ways to improve taxes on income and capital gains, but that is really different from a general wealth tax.
Rather, to continue the spirit of the top level comment, what is also now missing is the estate tax, which is/was around 40% (it's graduated too, but it tops out quickly). IIUC, the federal threshold used to be around $1M a few decades ago, and is now $10M - this was the anti "death tax" political issue you might vaguely recall. Furthermore, due to wider use of trusts, it's been basically eliminated unless your family is extremely unlucky.
Fundamentally, I'd rather just tamp down the amount of money given away to the rich - stop the government giving trillions of dollars to the financial industry to prop up the fictitious asset bubble pyramid scheme, and either let natural technological deflation happen or at least spend the money deliberately ala MMT.
But either way, something is required - the system we have right now has the government continually giving away gobs of money to asset holders, while doing very little to collect it back. This is exactly why these personal wealth bubbles continue to grow.
I think you'd be surprised. When the majority of people own nothing, it won't take much for the ruling class to convince them that taking everybody else's wealth for the greater good is the right and moral thing to do.