The wealth isn't particularly illiquid. That's not the problem I raise.
The problem I raise is that it largely is someone's jobs. If you want to tax the companies' overall value, part of the income from the work the companies do is going to go to the taxman. That money isn't gathering in a pile, unspent, today. So some employees are going to get fired or a pay cut, as a compensating cost-cutting measure. Which is fine so long as you understand that that's where the money is coming from. But you don't, right?
I'd argue you're looking at it incompletely. If wealth is accreting in individuals, then those individuals need to be taxed more than they currently are.
Society shouldn't care if Bezos' wealth is increasing because the value of Amazon is increasing or because he struck gold on his property: the issue is that he and others own an outsized share of global wealth.
The answer is increasing how progressive tax rates are, especially at the ultra high-end.
If Bezos or other post-unicorn founders have to decrease their ownership stakes in "their" companies to pay their tax bills, that doesn't decrease the competitiveness of the businesses.
It just decreases their ownership.
Pretending that decreasing the wealth of the rich is incompatible with efficient business is a red herring used to justify individual control. Businesses can still run and people can be employed: individuals just won't have as much exclusive control over them.
And before the 'Think of small founders!' fig leave gets trotted out to cover obscene wealth, we're talking about T500-scale companies that are well past that size, and whose market distortion arguably threatens small founders much more. (Remember 'Be the next ____' instead of 'Be bought by the current ____'?)
If wealth is accreting is individuals… but is it really?
When you have a nice job in a company, then as a matter of accounting, the shareholders have wealth. As I see it, that's just a matter of accounting. The first sentence of this paragraph says "you have a nice job" and IMO that description is closer to reality. The wealth actually is your skills and their integration into an organisation.
It follows from this view that "some shareholders accrete too much wealth" is more a complaint about accounting practices than about how goods are distributed in society. You do have that nice job, right? A few million nice jobs may be accounted for as one person's wealth, but the millions do have the jobs.
And indirectly that if you shape taxation based on accounting rather than reality, its effect on reality will be haphazard.
Nobody in the tax brackets we're talking about has wealth because of a job they. They have it because of ownership stakes.
The only way to value ownership stakes is via accounting.
Otherwise, we'll have the current system, where it's trivial for the ultra wealthy to both (a) have exclusive control over things and (b) not own them in a tax incurring sense.
Ergo, the solution is to flow tax liability along the same thing they want -- control.
The problem I raise is that it largely is someone's jobs. If you want to tax the companies' overall value, part of the income from the work the companies do is going to go to the taxman. That money isn't gathering in a pile, unspent, today. So some employees are going to get fired or a pay cut, as a compensating cost-cutting measure. Which is fine so long as you understand that that's where the money is coming from. But you don't, right?