I’ve known a few people who have gotten substantial windfalls ($5M+) for a variety of reasons. I also studied windfalls in college & law school.
One concrete lesson is this: if you don’t have a real plan in place when you get your money, you will- on average- fritter it away in 5-7 years.
Of the people I know personally with such an experience, some are on each side.
So even though such an event is unlikely, I’ve had a concrete plan in mind (but not written down) for 20+ years. I’ve convinced my parents to plan likewise.