I don't know about these specific scientists but often professors only get paid for the school terms and must rely on externally funded research grants for the rest of the year.
You're missing the parent's point. Another (one-time?) JASON who you might have heard of is Bill Dally. He was a prof at Stanford, including being the department chair, and is the chief scientist / senior VP of Research at Nvidia.
Needless to say, silicon valley senior VPs don't usually need extra spending cash.