I agree with your opinion. Even if corporate domiciles are moved to other states, the core R&D personnel and major infrastructure often remain in California. Therefore, the human resource network that Silicon Valley has built over decades cannot be relocated overnight simply by moving the headquarters on paper. The evidence that a wealth tax only causes an exodus on paper without actually destroying the industrial infrastructure has already been proven dozens of times.

Furthermore, even if paying a wealth tax forces stock liquidations that cause stock prices to plummet, unrealized gains do not flow into the real economy anyway. The key is the velocity of money, and from that perspective, unrealized gains are dead capital. Even at the cost of a stock market decline, if capital is forcibly circulated and pumped into wage increases or public infrastructure, the actual income rate and purchasing power of the general public with a high marginal propensity to consume will rise.

Then, thinking about why ultra high net worth individuals refuse to pay taxes, I believe they are idealizing themselves as the heroes of humanity. This means they think it is more ideal to strive for human immortality than to invest in 'inefficient' things like infrastructure through taxes. In other words, they believe they are investing more 'efficiently'. However, such thinking is neither rational nor logical at all. The reason is simple.

The idea that their class can be maintained when the base system collapses is dangerously complacent. From a programming perspective, if the OS crashes, how could the application layer possibly survive?

> ... even if paying a wealth tax forces stock liquidations that cause stock prices to plummet ...

Points, but I'll argue that: (1) Such plummeting would prove that the stock valuations were already very near the peak of a bubble, if not fraudulent. And (2) billionaires making that argument is a perhaps-legal but horribly immoral sort of Stockholm Syndrome move - telling a large number of equity investors "either I get my way, or things will get real painful for you".

> ... thinking about why ultra high net worth individuals refuse to pay taxes ...

I'll argue that most of the ultra-rich got that way through some combination of pathological obsessions with wealth and power. And their social environment skews very heavily toward (1) peers/rivals/friends/family with such obsessions, and (2) underlings/petitioners/fans/admirers with (at best) very unhealthy fixations on wealth and power.

> The idea that their class can be maintained when the base ...

Yep. https://en.wikipedia.org/wiki/French_revolution#Causes

My read of history that many in the ruling classes of other European countries really learned that squeezing their own lower classes too hard could end horribly for them. But human memory, even institutional, fades with time. And "this time is somehow different" is a perennial and seductive belief.