The CEO, now VP, was a university professor at one of the best programs in the world in a topic that’s extremely relevant, and had collected a lot of engineers and researchers who were skilled in this specialty

The engineers were largely Chinese, so I suppose they didn’t have much choice getting shafted on their common stock, and from what I’ve heard from other engineers, the offers weren’t extraordinary compared to similar positions at peer companies.

10 million is stretching it, but it's not uncommon for failed startups to get acquihired (their tech/customers are still valuable for another business) and the founder know-how is valuable for making those assets productive. So them getting guaranteed jobs with salaries is completely expected.

1 million over 4 years is not crazy depending on position.