In many ways, it is an obscene amount of control, and I don't disagree that this degree of wealth isn't ethical - even examples like Taylor Swift aren't from "hard work", but rather backroom deals, undercutting other artists, etc.

IMO, the best alternative is going entirely the other way. Tell all billionaires in the US that they are subject to a wealth tax, and attempts to fight it will result in freezing assets, expulsion from the country, executive removal, etc. Drive all billionaires out of the country, and let them set up shop elsewhere (they won't).

It's a punishment, though. Perhaps they should be punished, but IMO an easier approach is to say "well done" and to tell them that as long as this money goes somewhere for societal gain it doesn't really matter if they decide to pump tens of billions into making public roads the best roads in the country, it's better than them just having that money in a fund somewhere.

Where this will likely get dicey is in ensuring that this money stays in home accounts, and in defining what is taxable wealth, and fighting avoidance. That's where the system will be gamed, but ultimately it's different to avoid tax that goes somewhere to avoiding your money being spent by you for public good.