I like the podcast Behind the Bastards which frequently discusses grifters and how they got rich / influential. There’s a few episodes on COVID grifters that may interest you.

In general people on top came out even more so after each. Middle class and below always take the brunt of all those tragedies. Any specific person or named groups I could not tell you

The Koch brothers.

Mostly banks, oil and war machinery.

9/11 was a huge boost for the military suppliers, housing crisis got some financial institutions very rich for betting on the collapse. COVID mostly made medical suppliers rich, but also boosted weapons sales (more policing, border control…).

Usually it’s pretty easy to see, you just have to look for the interests. Also you can look at the laws and decisions that get passed after these events. Something like a plane crash or titanic sinking is more difficult. But you can usually say that people got rich before that happened and that’s usually one of the reasons it’s happening in the first place.

A fun and informative podcast for such information is “well there’s your problem” which talks about engineering disasters and the aftermath (it’s also very funny)

The already rich.

If war and they were in the Arms business. Krupp, Nissan, Boeing, etc. Krupp individually as a person.

If you’re already rich, Depressions/recessions are a fire sale for the rich. They buy up everything they can that suddenly becomes worth more in a few years.