I was a tenured professor who left academics for two reasons, the administrative nightmares of the university and department (to put it one way), and unrelated family reasons.
The year before I left they did a survey of faculty satisfaction at the university I was at, and found that, although about 2/3-3/4 of faculty reported that they were generally satisfied with their jobs, about 1/2-2/3 seriously wanted to leave (following an actual trend of faculty leaving in exodus). So these satisfaction surveys can be misleading and paradoxical, because the stresses are like that: you're acutely aware of the freedom and security you have, but also have very little recourse if things go awry.
As jobs go there is a lot of flexibility in some ways as a tenured professor (time, schedule), but absolutely none in other ways. It's difficult to move (although not impossible) and if you do you have very little choice in terms of geography or location. If you have family, you might be asking them to make huge sacrifices for you if they have better opportunities elsewhere, or can't move to be near you. Increasingly you're at the whims of fads in the field and among students: if you step back from doing what everyone else is doing for a bit, you get labeled as decreasing in productivity (note that I'm not talking about doing nothing, just referring to the fact that it's easy to churn out more papers or grants on things that are currently part of a trend, and where you can share work and credit; as a result, if papers or grant counts are your products, you will necessarily be less productive if you try something off the beaten path); if you challenge students (as did the author of the piece did) you get pushback from them. Increasingly I felt like academics was/is becoming full of bullshit in a way that no one wants to admit. It's fine to work in a field full of bullshit; the problems are when people lie to themselves and the public about it. The incentives are not to produce good, solid, insightful, replicable work, it seems to be to attract attention and entertain the maximal number of students.
My sense as a senior professor was that people in the same field in the non-academic sector were making significantly more money, and had more flexibility. So although they had to worry more about losing their job, if a department starting falling apart, or other conflicts arose, it was much easier to leave and move on to somewhere else where they wanted to be. Tenure is great if you're at a good institution, or if it works out for your family. If you're at a bad institution, or things go sour, and it's not good for your family, it is horrible.
I think if family considerations had not entered the picture I still probably would have stayed, or at least would have stayed long enough to leave for another university, but with the ongoing problems in the university and department, it was sort of the straw that broke the camel's back.
Professors are often exactly the kind of person who loves to work night and day on a topic of their interest. People also tend to judge the job for profs with tenure. The vast majority of professionals in academia are either pursuing PhDs, post Docs or untenured professors. Doctors have great job satisfaction once they are established too. But similar to profs the road to get there is among the most grueling.
The whole idea of tenure, is that the university expects the professor to be self motivated enough to warrant zero supervision or threat of losing their job.
A professors job is great for someone who is suited for a professors job. The traditional person who values other things may not find it to be as nice.