I don’t see the issue, if we say 1 billion is too much (I would choose a lower maximum personally) if their wealth in any way or form is above the max, they have to sell a house or some asset, society in the form of the government (or whathever is in place) take the money to be used for public interest project. It’s really not that punishing, they would literally be the richest people, and they would still have plenty of money/asset to enjoy life. They don’t need more.

“rarely”: so you admit sometimes the solution is “get rid of X” ? Then why would “get rid of billionaires” not be a solution for you ? To be clear I’m not saying we should kill them or physically hurt them in any way, we can simply reappropriate their wealth turning them into non-billionaire, also making it illegal for anyone to be a billionaire in the future. Why would that not work in your opinion ?