It is funny that a lot of the wealth we're talking about is not actual real wealth. These billionaires don't necessarily own physical assets that are valuable (although Gates buying up a ton of US farmland is worrying) it's all on paper and it would be wiped out in an instant with a stock crash.
I think, from memory, the US stock market has twice the 'value' as the real economy - which is bananas.
The problem is that even though their wealth is mainly on paper, the political equity they buy is real... and it's all in the name to increase the wealth gap because even though they have more than everyone else, it's never enough - and they're happy to burn the world down through authoritarian governments to get more.
Edit: I'm not sure we can count Covid as a proper plague in this instance... plague would normally redistribute wealth, when, like, a third of the population dies. Not to say your points aren't valid... but a proper plague would wipe out poor and rich alike in a significant way, whereas Covid deaths were a low percentage of total population and affected poorer people way more than the middle class and wealthy people.