An equally radical example would be a Wealth Tax, which would have a similar justification if one considers the wealthy to have a disproportionate amount of influence on the government (and the government has a monopoly on sovereignty in its territory). Another way to look at it is that those who benefit the most from a society (measured by their wealth) should pay back to that society in proportion to that benefit.

In fact, many successful countries already have a Wealth Tax, so it isn't such a radical idea[0], but I would argue that the tax rate for such a tax should be equal to the equivalent tax rate that the median citizen pays, as a percentage of their wealth. For example, in the US, the median household pays about $10k in taxes per year, and has a net worth of about $120k. That means that an equivalent Wealth Tax rate would be about 8% per year (with maybe a tax free allowance on the first $10 million).

[0] https://en.wikipedia.org/wiki/Wealth_tax#Current_examples