The most reliable way that has been found is to make everyone poor. Once disposable resources appear someone always becomes a more shrewd trader, even if means if production is otherwise equal. Then they trade those things for a greater share of the means of production...

High tax on the rich. We did it in the UK in the first half of the 20th century with tax as high as 90%. But to do that you have to vote it in and it's not really popular with the electorate these days.

It's popular, but no party run with that agenda.

Preserving wealth is actually an uphill battle. It likes to leak; the wealthy need the help of systems and institutions to keep their largesse intact. If you want it to diffuse throughout society, stop guarding it, stop bailing them out, and tax them like you mean it.

So many policy decisions are about who to throw under the bus; flip the incidence from "mostly people without wealth" to "mostly people with wealth".

The traditional method is fairly ugly but if someones actions kill enough people at some point it is reasonable to kill them too.

> How do you fix wealth inequality? That's what I want to know.

This has been a topic of research for a long time in social science. Wealth redistribution via taxation, education, and strong social safety nets. There is some deadweight loss due to taxation in a single-shot model, but allows for more stable regimes when considering the long term.