1. Competition and hierarchy. It is a brutally competitive profession. Even a lousy tenure track job might bring fierce competition. It is also a hierarchical world. Only the military, maybe, is more invested in "rank." It is easy to see why these two factors can create stress. If you won your job over many other candidates, then people might expect you to be good. Or if you look at someone not doing their job, it is easy to feel resentful, because 200 other people wanted that job. Hierarchy creates stress for everyone not on the top of the heap.
2. Politics. There seems to be a lot of time to invest in fighting against other people in your department. I'm thinking conflict is inherently stressful.
3. Deferred or non-existent rewards. Hard work brings some rewards, but they might be years in the making. Gratification comes in extremely small doses, and sometimes years after something you did. It takes a special kind of personality to be cool with this. If you think you are good, and have done good work, and have competed to get where you are, but then you get a .08 percent raise, it might be stressful.
4.The gap between reality and desire. The gap between what academia ought to be and what is really is causes constant stress. If it just was the job that it was, with no expectations, that would be one thing. But you can't just say "It is what it is," to use my least favorite catchphrase of this decade. "It is what it isn't supposed to be." Having to direct a dissertation you know won't really contribute to scholarship. Wasting your time with remedial instruction for even graduate students. Then the gratification comes when something ends up going the way you think it normally should.
That's just the beginning. I've experienced all of this, and am now at a point I don't have to quite as much.
Here is very stupid comment on the CHE:
Just like the wrong people become doctors for all the wrong reason -- money and stature but no bedside manner or empathy -- the wrong folks aspire to professorships. Surveys of male professors found the major reason for their vocational choice was "being their own boss." We get to do what we want and get left alone. What about using their expertise to influence public policy? Not in the past 80 years. How about attracting the most charismatic instructors? Nope. These are some of the most boring people in the human race.First of all, being one's own boss is admirable. The human need for autonomy is fundamental. Why is that so horrible? Most academics I know are very interesting. They have traveled, read books, know languages. Secondly, the dissertation process makes you go out on your own, be autonomous. Nobody really holds your hand and tells you what to write. (The writer of the comment didn't seem to realize that the two paragraphs he wrote contradict each other.) Even college kids refer to themselves as kids, so what is that about? Finally, academics tend to value autonomy in other people as well. The question of "what does the professor want" is frustrating to the professor because we don't want anything except for the student to make up his or her own mind. I hate being told what to do and also telling other people what to do. Does the public think we want to spoon feed little bits of powerpoint sized knowledge?
Worse yet, the very process of making it through the PhD sausage factory produces the lousy corp we see in the classroom who refer to their legal adult students with the pejorative "kids." Only subservients are awarded doctoral degrees. You must kiss up to your committee members to draft the dissertation that they would have written themselves. No wonder those new PhDs will run the courses as obstacle courses where students seek out "what Dr. X wants to hear."