Why did you leave?
I left graduate school (organic chemistry) with a Master's degree after 3 full years. I had been doing semi-successful research for nearly that entire time and received praise from my advisor for my research and laboratory technique. I had passed all of my cumulative exams, and I was working at a top school.
Leaving early was not an easy decision. I had entered graduate school 110% determined to earn a PhD, no matter what. [This perhaps stemmed from my failings in childhood; quitting drum lessons and the junior-high basketball team had left a scar on my psyche, and I was dead set against ever quitting anything again.]
I've since learned not to deal in absolutes. I had to adapt to a changing situation.
Eventually, clinging to my desire to earn a PhD actually made me miserable. I had joined my group under the premise that I would be allowed to work on a synthetic project. I had devised the synthesis independently. It was interesting and very challenging work. But everything changed when this primary project was canceled, despite making significant advances over the course of about 18 months.
My advisor wanted me to take up a methodology project in its place. I had little interest in the work and voiced my concerns. Nevertheless, due to my laboratory skills and the importance of the work, my advisor assigned me against my will. I asked the department head about changing groups, to no avail. I tried to work on the new project diligently, but I could not get excited about it. Results were unspectacular and barely publication-worthy.
Ultimately, it became very clear to me that earning a PhD while working on this particular project was not going to pay off well. I would be forced to do at least another two years in post-docs before I would be considered a good job candidate. As landing a job in industry was the end-game, I made the tough decision to leave.
Where are you now? How does the decision look to you now?
I have never regretted the decision. As a Master's-level organic chemist, I find it much easier to find interviews and jobs than PhD chemists. I can usually find at least three interviews (5-7 in the "pre-Chemjobber" days) any time I want to change jobs (or get laid off!).
I have built a solid reputation as a hard worker, and I have the ability to perform independent research. As such, I have always been promoted to PhD-levels of responsibility and salary with each employer. I have found it virtually impossible to progress beyond entry-level PhD positions, but I make a good salary and I'm completely satisfied where I am. Besides, I don't have the work-related burdens of the PhDs I work with, and I leave my work at work every night. I feel blessed.
That's my story in a nutshell. I don't recommend anyone enter graduate school lightly (I pondered the decision for at least a year and sought a lot of advice from elders), nor do I recommend that one leave flippantly (it took me almost a year to decide to leave early).
But each person and each situation is unique, and "quitting" grad school may work out in your favor.Thanks to "G" for their story.