> But, to be nuanced we also need to address the core question: "are billionaires bad for the rest of us?" That is the premise of a wealth tax, at least the currently popular one.
Suppose we impose such a tax. How will that affect wealth formation and accumulation by not-yet-billionaires, and how will it affect existing billionaires? As you say, Bezos and Buffet would continue being billionaires, but if new billionaires became an impossibility, then such a tax will essentially be creating barriers to competition with existing billionaires! That would be a billionaire protectionist measure disguised as a populist measure!!
If we see existing billionaires support such a measure, then we'll know they likely don't see it hurting them. Kinda like when Buffet advocated for higher income taxes knowing full well he has no taxable income (all his "income" as most people imagine it is just unrealized -and therefore untaxed- capital gains).
Also, the biggest problem with any new tax is that without a hard cap on rates it's difficult to predict what it will be in the future. When the income tax was proposed in the U.S. it was said it would never rise above 5%, but marginal income tax rates in the U.S. have been north of 90% (yet, of course, these never reach the super rich as explained earlier). A wealth tax might come with "it will never be higher than 0.2%!" claims, then rise to 5% anyways. If it comes with such a claim, that limit needs to be baked into the Constitution.
Besides the intended political and economic effects of a tax, its unintended economic impact, there's the question of how much revenue it will raise and what that shall be used for. Leviathan never shrinks, so a decision to enlarge it should not be made lightly.