My experience was very similar. While I was in the land of postdoc fellowships and part-time teaching, it was a great job where I gladly accepted low pay in return for freedom to work on my own projects and structure my time independently. By the time I was a few years into a tenured post (at a European university), the amount of administrative drudgery, committees, useless meetings and other BS entirely unrelated to my skillset as an academic had grown tremendously - enough to make it quite easy to quit when I saw opportunities in the software industry. When I look back at it now, I still bristle a little at how much worse it got over the years, almost feels like a bait-and-switch. I have several other friends who've since left their tenured positions while still young, all of us with this feeling that we were stuck in a type of work we really hadn't signed up for.
34. other profs i've known who quit academia were in their late 30s/early 40s. (and of course a ton of grad students and undergrads who stopped much earlier, and people who never got jobs and eventually worked outside academia, but that's much more common)
