TL;DR: Norway imposes a wealth tax that taxes unrealized gains at approximately 1% annually. "Wealth" here includes the book value of private companies, which presents cash flow problems for founders of startups with high paper valuations (like the author, who founded unicorn Dune Analytics).
I'm still finding it hard to be terribly sympathetic towards the author, and the constant Ayn Rand references don't help. If you're worth 100 million dollars on paper, is it really that hard to come up with 1 million to pay the taxman? Sell 1% of those shares, get a loan secured by those shares, etc.
Not to mention that the general findings from Norway's wealth tax is that it works. A few millionaire's leave but the benefit far outweighs the cost of some capital flight
https://www.reuters.com/business/norways-wealth-tax-trades-m...
I still prefer Warren's proposal in the US which only proposed a tax above a net worth of $50m. The biggest criticism of wealth taxes is the massively complicated added bureaucratic burden of measuring everyone's wealth. Only about 0.14% of USians have a net worth above $50m.