How about this? Once you reach $1b in cash and assets, regardless of where that cash and assets are parked, you get a trophy saying “Congratulations you did it!”, and then we take the remainder of your cash and assets and use it for the advancement of humanity. Providing food, water, and shelter for every human being on the earth. We use it to build high speed rail and local transit infrastructure that is free or low cost. We can even name them after you and put up statues. We use it to provide healthcare and education to everyone. At the end of every year, if you have >$1b in combined cash and assets then you get to fill out a form saying which combination of the cash and assets you want to keep up to $1b, and the rest is given to the state.
This is the peaceful, “reasonable” option that even liberals should be able to get behind. But they will make excuses about how they deserve it and the policy is wrong even as they are being exploited.