Because I don't believe that most people are really aiming to be multi-billionaires, I think most of the effort comes from people trying to reach financial independence at various levels of cost of living.
A wealth tax doesn't just affect multi-billionaires, it guts all accumulations of wealth. If anything, billionaires are most able to shrug off a wealth tax. Your average Financial Independence strategy (pursue a high income to accumulate a sizeable warchest of assets quickly, then passively live off the illiquid assets slowly) is severely gutted by a substantial wealth tax that aggressively drains saved assets.
Do you feel like a wealth tax starting at the 50,000,001th dollar of 2% until you get to a billion is "gutting all accumulations of wealth" or would harm the average financial independence strategy?
No, probably not, assuming you keep it accurately adjusted for inflation. This will likely impact the next tier of wealth: tech startup founders. Either startups will represent a tax loophole or the wealth tax will slowly drain the illiquid assets of founders and early employees during the startup phase which nowadays often have a notoriously long gestation period.
