I think most people are OK with the $100M+ thresholds but are uneasy about the incentives this sets up where the government can extract large amounts of money f

I think most people are OK with the $100M+ thresholds but are uneasy about the incentives this sets up where the government can extract large amounts of money from inflation which is in effect a tax on the poor and in general benefits the asset holding rich. And there is a reasonable expectation that the bands will lower over time in both nominal and real terms to cast an ever wider net. I have long maintained that this has to happen mathematically because the government needs more money and there are not many places where they can get it. A high enough unrealized gains tax coupled with a high enough inflation is in effect a wealth tax. A high enough wealth tax can in effect capture a large chunk of the profit from the wealth, theoretically it could go higher than 100% of profit (e.g. 50% income tax, 6% inflation, %4 profit on wealth = %2 profit after taxes - %3 tax on nominal asset gains = -1% p.a. in real wealth. It has the real potential to be confiscatory in nature. Even the risk of this would likely result in capital flight so this tax plan would have to be exported globally to limit the number of places that capital can escape to.