The freedom and unstructured time to explore fuzzy problems is unmatched.
An assistant tenure-track professor in CS or CompE is going to make maybe $100k for 9 months of service, and really it's more like 30-32 weeks. I don't know any other job that gives you 6-figure salary and lets you basically do whatever* you want for 42% of the year.Is a 2x salary increase worth giving up that kind of time? For me I think It'd have to be a sum where I could retire much sooner, but what I would imagine myself doing in early retirement is the research I'm doing right now.
I know a lot of people that made the same decision as this author, and they do report they miss the freedom of summer that academics get.
* - you get 6 years or so to prove you've spent your time wisely.