> like a max between an income-based tax and a wealth-based tax.

I'm not sure if you mean "mix" or "max" but I think my answer might be yes to both. :) What I'm proposing is that the rich continue to pay an income tax like everyone else, but above a certain wealth threshold they need to be assessed for paying a wealth tax. Any amount they pay in income tax can be counted towards their wealth tax, so they don't get double-taxed and don't have to worry about paying more than the median citizen (proportionally).

> I believe in the benefit of doubt.

The best philosophical approach to this that I've found is Rawls's "veil of ignorance"[0] thought experiment. While it is difficult to completely rule out the possibility of bias when asking someone to come up with a policy that has harsher effects on people who aren't like them, I feel confident that I would be willing to trade my current place for the place of a billionaire living in the sort of society I'm proposing.

> As far as I'm concerned, if someone is rich, they deserve to enjoy the fruits of their labor, not to a lesser extent than me.

What if the rich person became rich by inheriting money, or winning the lottery, or being lucky in some other way (e.g. finding oil on their property, or being born with the looks of a supermodel, or being the first to patent an obvious idea)? Societies do try to address these issues with different policy measures, but all I am asking is that the rich "suffer" the same amount as everyone else (i.e. as the median person in their society).

Paying a given dollar amount in tax obviously feels much hard if you have close to that amount in assets, compared to if you have so much money that it's literally uncountable and you wouldn't notice if that given amount were taken from you. So I think it is the poor that we should be giving the benefit of the doubt to when they say that the current system is unfair to them.

> I personally know lots, really lots of people who work much harder than me, and make more money than me.

And I know people who work much harder than me, and make less money than me, because the market doesn't value their work in the same way as it values mine. Sadly I see more people trying to protect the status quo for idle billionaires than trying to change the system so that the hard-working poor are rewarded according to their intrinsic worth as human beings, rather than how little the rich can get away with paying them for the value extracted from them.

[0] https://en.wikipedia.org/wiki/Original_position