I think part of that reason was because it was at that point that the day-to-day, tangible outcomes of the work I was doing generally disappeared. I've hinted at this before, but it's time to give this reason its own post.
Early in grad school, my work had concrete outcomes and a clear purpose. I'd do reading for class meetings, where the tangible outcome was participating or listening to a good discussion on a topic - learning more about my field of study. I'd write papers, for the tangible outcome of a course grade (or to finish my MA). When studying for my qualifying exams, I had a list of readings to do, and could cross them off the list as I completed them. Tangible outcomes. I could see what I was accomplishing every day, and was working toward a concrete goal with a defined end point.
Once I finished my coursework and my qualifying exams, I moved into the world of teaching and independent research. The teaching, I loved. Writing and delivering a lecture, even grading a stack of papers? I'd feel accomplished. I could see what I'd finished that day, and I felt like I'd been working.
Research (of course, the bulk of what your record as a grad student will be based and evaluated on) was different. Research tasks dragged on and on, with very few end points. Every draft of anything was met with more and more comments, more and more recommendations of additional articles I should read or another angle I should take on a particular piece of my writing. So I'd go think about those (often conflicting) comments, and read the recommended additional research ... and often would make very few concrete changes to what I was writing on any given day. So an entire day of reading and thinking would go by ... and I'd be left with nothing completed.
Every draft of a paper is met with additional comments and revisions. (Almost) every journal submission is met with reviews that you have to address. Every day of coding data will likely result in you needing to re-code it again on the advice of an advisor or reviewer. You will likely have a hard time some days describing to other people what you did that day or that week. It's not that you objectively aren't doing anything ... it's just that there is rarely a tangible pile of work to which you can point and say "see that? I did that today."
(This was placed in sharp contrast for me when I started working part-time, by the way. I wasn't doing groundbreaking work; however, I found myself more and more pleased with the fact that at the end of the work day, I could leave my office feeling pleased with the pile of work I'd completed that day. I'd done something.)
Now, maybe you're reading that and thinking "what is JC talking about? That sounds absolutely horrible to me. A day of processing paperwork sounds torturous. But a day full of thinking? Perfect."
And that's great ... for you, and those like you. But that doesn't work for everyone, and that is something that academia fails to acknowledge.
As I've said before, I'm not arguing that academia is terrible or that everyone should quit. What I am arguing is that an academic life is not right for everyone who starts down this path, and that it's okay to think about other options.
If you're someone who enjoys seeing tangible outcomes for the work you're doing on a regular basis, it is very likely that you will be unhappy and frustrated in academe.
And I'll end this post with a comment from reader JMG of the blog 100 Reasons Not To Go, in the post that addresses a slight offshoot of this "tangible outcomes" bit very well - the idea that there are few tangible rewards for the work done in academia. In his/her comment, JMG addresses the inherent reason why this "no tangible rewards" issue can be particularly hurtful to those of us in academe. Namely, it is particularly harmful because we academics are taught that what we are doing is supremely meaningful and important:
Students honestly think they will make this everlasting contribution not just to their field but to all of arts/science/medicine/law/all of the above. (...) The problem arises when, slowly and painfully, this is shown not to be the case. It's one thing to have a dull job where the only tangible benefit is getting paid and to be fully aware of this going into it. It's quite another to think your job will be inspiring and world changing and it turns out not to be the case.Add to that the very distinct possibility that on a daily basis, you won't be able to see what you're even accomplishing, much less be rewarded for it?
Well, as I said above ... that might be fine for some people. But if you need concrete outcomes and rewards, academia may not be for you.