I'm fine with changing the alpha value, and finding an optimal alpha value is actually what we should be doing IMO. But we can't act like it's not gonna still be close to some type of power law distribution at the end of the day.

The wealth distributions we see have a mathematical flavour to them but are the result of a system created and governed by humans.

In fact vast disparities in wealth can only be created and sustained through significant social effort.

It takes an incredible degree of social co-ordination for multi billionaires to exist. Outside of a strong rule of law you have be to a strongman or warlord to keep your hands on all that stuff.

As a society we could choose to cap wealth. For example we could say "it's illegal for an individual to own more than a billion dollars worth of assets". The excess would effectively be tax.

I can immediately think of a huge number of problems with this (oh no, all the multi billionaires leave!, offshoring, transfers between family members, "schemes" in general) but it's obviously possible to pass this kind of law, were there the social will to do it.

It is not possible to amass huge assets without deep support from society at large. Police, judges, guards and the goodwill of the public are ensuring the safety of the billionaire's property.

Indeed, the very concept of asset ownership exists only by virtue of social recognition. We make up the rules that define ownership/property/wealth/etc, they are not handed down by God, and we could just as well define/design them differently (as your example of a wealth cap astutely illustrates).