A simple example, would a tax on wealth above 100 million USD discourage startup founders? I don't think so.
The AMT was put together to hit the top ~150 people in the 1960s. Because of how the underlying system changed and it hasn't, the AMT now regularly hits people under $100k and is only likely to drift lower.
Congress has a bad track record here.
If we do, then more startups will get off the ground. Some of them will make it big, and their founders will get rich. Our action will have made society more unequal.
So clearly we should leave it, right? But that doesn't seem right. So maybe inequality is not exactly the right framing of what we care about.
We've had progressive taxes for a long time, and that's good, but they have not prevented inequality. So again, is it really the measure of goodness?