If your goal is to eliminate billionaires (just billionaires? where's the cut-off before Unstoppable Evil comes in?) why tax them? Just outlaw 'excess' wealth and take it. Super-curious, because I've never seen this question answered, but where is that cut-off? I'm going to guess it's way below $1bn actually. I'd guess $50m? $100m? Go on, pick a figure!
Because taxation can be gradual, and doesn't represent a legal issue with the prohibitions against post facto laws. We don't have to set a firm threshold to strongly disincentivize billionaires. If it gets to the point where above 20M/Y has a marginal tax rate of 95% and above 50M/Y has a marginal tax rate of 99%, then there's almost no incentive to earn more than that.
Btw, when the government has taken all the billionaire's wealth, what are they going to do with all those yachts and private mansions and so on and so forth? Who's going to run all the companies no longer owned by their previous shareholders? Worker's committees? I'm sure those would be highly effective....
The yachts and mansions operational costs are a small fraction of their value, so once they're built, you could rent them out for the still wealthy, but not as society destroyingly affluent. Or their owners could keep them, since very few of the billionaires would be in danger of having to liquidate them even if they stopped being billionaires. Even a few hundred million would serve fine to keep those operating, even more so if they defrayed operating expenses by hosting parties with cover charges or renting them out. They're wasteful and usually tasteless sure, but since they exist, may as well use them until they no longer exist.
The companies would have their stock purchased on the market, for those that are publicly traded, to pay the tax bills. Private companies would be harder, but employee ownership is quite effective at operating and preserving a company, it's just not the primary economic model we see used for explosive and exploitative growth, because it turns out that employee exploitation and shady business practices aren't winners with most employees.
Anyway, here's my take - billionaires (and free market valuations) are not the problem. Inequality isn't a problem, it's a sympton of a problem.
Let me put it this way, if I'm ok (I can pay my bills, I'm safe, free and able to pursue basic happiness in a society that protects me) then what does it matter if someone else has 10,000x the wealth I do? If I worked for a company that supplied parts to another company that builds megayachts for the superrich, I might even be pretty pleased there are people buying those things.
Come on, what's the ACTUAL problem here???
The problem is that that much wealth means that there is a massive imbalance in influence and power, and that those billionaires can use that to make the society not protect you. If that societal protection and freedom were actually iron clad, it wouldn't be a problem. It's that the level of wealth accumulation is only enabled by demolishing protections for people at scale.
If, when in a thread about rich people sexually abusing children and getting away with it, BECAUSE THEY ARE RICH, you are asking what the problem with letting people be rich, cause you're totally safe and protected, then you have to take a long hard look at your own convictions, as well as if you're actually safe, or just unattractive to predators.
Then again, you're also the one who got the Andrew thread locked, so maybe we have a mismatch at the values/morals level.