The problem is that there is no fair way to account for true costs of what we all use. The force multiplier on all our efforts of society is immeasurably huge. Without society we would be illiterate ape creatures collecting berries and digging for roots. Even the greatest of us is adding no more than a few grains of sand to the beach. The only fair way to allocate ownership of all that inheritance would be to say it is collectively owned by all of us. No billionaire, or anyone else, paid a fair price for all those thousands of years of collective effort they use each day and you can’t make anything worthwhile without it. If we paid a fair price for all the laws, technology, culture, organisation, infrastructure etc we use, it would be 99.9999% or more of everything we make. So no wealth or inheritance can ever be fair. It’s all just advantage achieved by taking an unfair share of what everyone else who ever lived collectively made.