The problem with this hollowing out of the regulations government used to have, is that people react by jumping for extreme, impractical things like "wealth tax". Nobody is going to go for the idea that the government comes around and explicitly collects a significant percentage of everything you own every year. (And they already do much of what they can get away with through inflation and real estate taxes).
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.
