A wealth tax could be fair.
Arguing about government ownership is a red herring. The only thing that allows a multi-billionaire to acquire such wealth is a state with laws, police, courts, and armies to support their claims to ownership. The idea that Bill Gates should pay no more in taxes than a pauper is absurd and everyone knows this.
Bill could TRY to protect his property from the starving masses using a private security force. And it would probably work too, until his chief of security decided to take Bill's place.
Government at its best is a mutual insurance company allowing sovereign citizens the opportunity of living in a stable society where everyone is not spending a huge percentage of their time and resources just protecting their life and property.
Even if every human life is of equal value, their property certainly isn't, and it takes proportionately more to protect the "rights" of the rich.
What's so hard about this concept?