Should dropping out of a PhD program be treated the same way as quitting a regular, industry job? I personally see no practical difference between dropping out of a PhD program and quitting a regular job, at least considering the way PhDs work in the US, especially in STEM fields, but I'm sure many people will disagree. Please let me elaborate why I think that way, and let me know if I'm being too naive or missing an important difference. I really want to see a difference, but so far I can't find any meaningful one.

At least in the US, PhD students are often employees of the university, they hold a research assistant position, get paid a salary and declare it as taxable income. Most people I've talked with in academia agree that the main point of doing a PhD is working on your own research rather than taking classes, which should just be a complement. That sounds pretty much like what you do at a regular job than what you do in a master's or undergrad degree; you have a main project to work on, and maybe some ocasional training sessions that might be useful for your work. Some people like to point out that dropping out of a PhD program has some sort of stigma attached to it because it means that you couldn't finish something you began. However, I see no difference between that situation and quitting a regular job where you had a long-term project that you realized was going nowhere, had no future or was needlessly stressful, and you decided not to waste your time trying to finish it and find something better. My view is that if you leave a PhD program with no degree, but you worked for some years as a research assistant, you can still write it down in your resume as a research assistant position you had at the university, so it's pretty much just another job for practical purposes, I don't understand why the fact that you didn't get the degree is such a big deal for some people.

Something I should emphasize is that I'm biased in my thinking towards STEM fields and people who enter PhD programs, but have no intention to stay in academia. If one wants to become a professor, dropping out of a PhD program is obviously a big deal, since it's often a requirement, but I'm talking about people who do PhDs mainly to get better jobs in industry. I know some will point out that that's probably a bad reason to do a PhD to begin with, but honestly, I've met many PhD students who think that way, especially in computer science and other STEM fields. Regardless, many people also begin a PhD because they are really interested in working on a specific area and that area happens to be developed more in academia than in industry at some point in time (machine learning is a good example), but they don't have any intention of staying in academia and plan to get a job in industry afterwards. Still, they might get disappointed about the area or the environment along the way, the same way one might serious negative aspects of what seemed at first as an interesting job.

I'm especially interested in reading people who disagree with any of the specific points I mentioned before and why they are not valid analogies between dropping out of a PhD program and quitting a job. If this looks more like an open-ended discussion rather than an appropriate question for this site, feel free to put it on hold, but I'd appreciate if you can point me to a more appropriate site where this kind of discussion can take place. This site is the only one I know where well-informed academics congregate.
This answer addresses the idea that the work a PhD student does is just like work at another job, and therefore quitting the jobs should be viewed the same. (My answer suggests that it should be unusual for people to enroll and then quit without there being a serious problem, and also that potentially elements of society might place stigma on that action to keep people from wasting educational resources.) There also seems to be an indication in the question that people should be free to casually start positions as Ph.D. students without the intention to finish the degree. (I may be overstating the poster's view, but that extreme version is what I address below.)

I believe that for an individual, leaving a program or leaving academia can be the right choice for all involved, and that work as a graduate student is valid work experience to list on a resume. However, it is harmful in the long term if people enter graduate school without the intention of completing the degree.



A huge part of the compensation for being a PhD student is funding one's classes, training, library access, access to lab materials, potentially travel funding, and access to smart peers and smart professors. It costs a lot to create a learning and research environment.

For instance, a postdoc working a similar job in a lab will get paid more; partly because they need less supervision and training, have more experience, and have more responsibility, but also because the professor does not have to fund the tuition and student benefits for that postdoc. And a professional lab worker should be paid even more.

If, as you say, being a PhD student is just another job, then people who do not value all of the parts that support academic success could value those things at zero and realize they are getting a very poor wage. They could work at a private lab for the same work--but without the support for learning and autonomous research--and get paid much more for the same style of tasks.

Again, it costs a lot to create a learning and research environment, and universities are investing in their students' success. Hoxby has a model of university funding that likens university founders (and later donors) to venture capitalists investing in human capital and in research: http://www.nber.org/papers/w18626.

As Hoxby writes: "Because some of the students' returns will presumably be social, the obligation on them can be multifaceted.  Those who earn private returns on their human capital can be asked for gifts in the form of money. Others could be asked for gifts in the form of expertise. Others could be asked to use their political influence to sure that the university is treated well by the government.  And so on." Hoxby 2012, p. 19 

If people are taking Ph.D. positions as mere jobs, they are less likely to fully contribute to the educational environment, less likely to take full advantage of the costly investment in their educational environment, and less likely to give back to the institution to help it sustain itself.



TL;DR: It is extremely short-sighted to think that students are merely workers. It is to academia's detriment if students, professors, schools, and governments act as if they are.

(These models and my thinking are largely based on the U.S. system, which the poster addressed. I would be interested in thoughts on how this compares to other funding models.)



Note: I do not intend this answer to say that grad students are or are not employees for the purposes of unionization or other purposes. However, I believe this account of why schools fund tuition for advanced students as an uncertain investment helps us understand why the rebated tuition should not be taxed as regular income (as a recent US tax plan suggested doing).