Doesn't that argument depend on their net worth now being equal to (or at least not significantly greater) than it was before the pandemic (or market pricing in the risk of same) started? I.e. yeah, his net worth went up, but it went down first, so it's just coming back to "normal".

That doesn't seem to be the case here- Amazon's (and thus Bezos's) dip in early 2020 is practically invisible compared to its growth since then March, from what I see on https://finance.yahoo.com/quote/AMZN?p=AMZN

So...

Imagine you own a modest $300,000 house. A city inspector comes by and finds that your property is located on an old toxic waste spill- its value drops to $225,000. A week later, the city finds that they've made an error, and there is no toxic waste- and, in fact, that in doing the testing, they discovered deposits of incredibly valuable minerals on your property, so now your house is worth $450,000. A month after that, you get a tax bill in your mailbox for $45,000, 30% of your $150,000 asset gain. (These numbers are based (rounded) on the actual data.)