Not all of that money goes to the developer, but also to the seller places and other places. You'd also still have to pay income tax.

Ideally, there'd just be a 100% income and wealth tax after having say, 1/10,000,000th of the world's total GDP. Without any loopholes.

With a world GDP of approx. $ 102 trillion, or 102 billion if you use the long scale, that is about $ 10.2 million you would have at max.

I think it fair up until then, exploited after that. With that money, you can practically buy anything to your heart's content anyways.

How about more brackets?

-- Practical scenario --

Suppose you had a wealth of 10 billion. The lowest bracket is a 3 billionth of the world's income, so say 34k. That's taxed 0%.

The lower middle is from there til 1.6 billionth of that income, around 64k. Taxed 35%.

Upper middle, around 1.6 billionth til 1 billionth (around 100k), taxed 65%.

Upper, around 1 billionth til 1 millionth (10 million) of world's GDP, has about 99%.

Highest has 1 millionth and beyond. Let's assume the world's GDP is 100 trillion for ease of calculation.

So, you have 10 billion. 10 bil - 10 mil. 9.99 bil, all removed, used for public works.

10 mil - 100k, 9.9 mil. Taxing 99% of that 9.9 mil gets 99k.

And so on, until you have a smaller but respectable amount to play with.