Thanks for the write up, but you yourself are positioning an extreme example here and extrapolating it. The fundamental principle that underpins a wealth tax (as I see it) is to bridge the gap between the rich and the poor, and to reinvigorate the economy and redistribute wealth...which is ultimately what we should be aiming for in an egalitarian society.
I'm going to use a hypothetical example with arbitrary numbers, but the principle that underpins the example is what I'm getting at.
Firstly - for a Musk or Bezos who have most of their wealth tied up in their own companies stock - let's say hypothetically, the current tax models exist, but there is also a wealth tax for people who own over £10m in stock, whether it's their own companies stock or whatever (and let's just totally ignore property portfolios, bonds, gilds, forex, crypto what have you for the sake of simplicity). This is saying anyone can own up to £10m worth of stock totally tax free, and will be paying income tax, CGT (but I would actually change this tax if this wealth tax is implemented), IHT etc at the normal rate.
What I'm suggesting is that for anyone that crosses that £10m barrier, a wealth tax kicks in of 2% up to and including £100m, meaning the absolute lowest you pay is £200k is payable at the lowest end and £2m at the top end. If you're a owner of your company and your shares are worth over £10m, the benefit of this wealth tax is (as I see it) two fold -
1) Your liquid assets / cash reserves can pay off the wealth tax payable - basically taking money out of an idle bank account which is earning interest and putting it back into the economy.
2) You sell shares to cover the cost - basically taking untapped wealth held in a share and putting it back into the economy.
And yes, I've plucked this £10m-£100m banding out of thin air to make a point, but I would have a further banding of £100-500m where the rate would be 1.9%, and then £500-1bn of 1.8%, and so on (but bear in mind these figures are crude, and arbitrary, and it's the underlying principle which is what I'm getting at).
To your point 1 - if your shares go up from £10m, to £20m, then again, the process repeats and in that years time you would have made income from your business via wages, BIKs, dividends, as well as the benefit of each share you've owned being worth double than what they were last year. So, a win-win for the owner of the business as well as those in poverty as this wealth that's tied up will be redistributed in society. If your shareholding falls under the £10m barrier, then there's nothing to pay. If the value falls from £20m, to £15m, then your liability is reduced from the previous year. But stays at that 2%. Also, bear in mind, the tax of 2% for idle cash is probably less than that same amount of cash is earning interest sitting in a bank account for these high net worth types.
To your point 2 - this goes to my earlier point on you've positioned an extreme example. The state wouldn't be the owner of the shares, but would receive the monetary amount required from either the release of cash reserves sitting in an account, or the wealth held in a gain from the selling of a share to cover the liability. Again, the principle is about redistributing the wealth and reinvigorating the economy. In terms of control of the company, Bezos and Musk only own 10% and 17% of the equity of their respective companies (but may have a higher proportion of the voting shares), and Bezos only recently stepped down as CEO of his anyway, so I don't buy into the control argument. I'd be interested to know what shareholdings companies in the £10m-£100m are owned by >50% shareholders. I don't have that info to hand.
To your point 3 - I'm not sure I agree - whilst there would be a stock price decrease, if, and only if, the 2% liability has to be covered by a sale of shares...which when you're operating in the Bezos, Musk stratosphere wouldn't likely be paid for by the sale of shares. And we're talking about 1 point in the year here. If your company has an amazing year, and you see your share price increase by 10,15%, the amount it would decrease due to a sale will be much smaller. Tesla's share price for instance increase by 740% in 2020. Amazon's was 74%. The amount of decrease is a minor dip when compared to their overall increase.
To your point 4 - Part of this is answered in my 'to your point 2' section. But in the history of finance, there's never been a major destruction of a great company due to the reason you posited. The main destroyers companies tend to be ineffective or corrupt management, poor cash flow, or changing macroeconomic/technological environments. I'd be interested to see any examples that have led to the destruction of a company due to the reason you said.
Now the flip side of all of this if a person hoards cash instead of tying it up in stocks - how would they be affected by a wealth tax that starts at £10m. If they had £10m cash sitting in an account, they could either -
1) Pay the £200k to the government - again, taking cash out of an idle bank account and paying it over to the government, thus stimulating the economy via public utilities and services.
2) Spend £200k reducing the balance to be £980k...via investing (which comes with its own tax breaks if they are EIS, or SEIS), on charity (which comes with its own tax breaks), on buying a fancy new car (which comes with VAT), but this is all driving to the same point - essentially taking this trapped wealth and redistributing it into society.
I'm not saying the above is a well thought out strategy that is robust enough to work in every facet of society, but the underlying principles of a wealth tax are sound and make sense. The way we're currently headed as a society is pretty depressing. Going by current estimates, Boston Consulting Group have said by now (i.e. 2021), that 70% of US wealth is held by their richest 1%. Other estimates say it's the top 10% in the US that own 70% of the wealth. Whatever the true statistic, the only way to get some of that wealth back into the public domain is via a wealth tax, that will serve both the rich and the poor. It's by the redistribution, that the economy can be reinvigorated as well as alleviating poverty.