Nobody in this thread has suggested 100%, nevertheless, most of the billionaires pay nothing anyway and always have done so.
However, in the example I have given, I see no reason why they would even be able to justify half of that money being given.
In my opinion, something workable is like this:
Each generation of estate holders is allowed to pass on all of the capital gains they have made on the total capital, plus half of the previous generation, and then 10% of the total capital, minus primary residence.
Let’s say the policy works from 2020.
George Grosvenor inherited a $50bn estate in 1980. He accumulates an extra $5bn to the estate and dies in 2000.
Charles Grosvenor inherits a $55bn estate in 2000. He accumulates an extra $7.5bn to the estate and dies in 2020.
Richard Grosvenor inherits the $62.5bn estate in 2020. He keeps the $7.5bn of his father, and $2.5bn of his grandfather. He then takes a $5bn slice of the initial capital of the third generation prior. Hence, his estate is now worth $15bn.
There is a flaw though - or a fair and just compensation, whichever way your political view swings:
Someone Gates inherits a $5 000 estate in 1940. He accumulates an extra $15 000 to the estate and dies in 1960.
Someone Gates inherits a $20 000 estate in 1960. He accumulates an extra $20 000 to the estate and dies in 1980.
Bill Gates inherits a $40 000 estate in 1980. He accumulates an extra $70 000 000 000 to the estate and dies in 2030.
Rory Gates inherits all of the estate in 2030, taking $70 000 040 000. He takes his fathers $70bn, his grandfather’s $10 000 and $2 000 from the initial estate. Hence he is now worth $70 000 012 000.
Obviously inflation and interest erodes a lot of this, but not significantly enough, as most of this will be based on land. Very few billionaires et al have their net worth in personal finances rather than real estate.