I recently created a video on my YouTube channel about writers and "the day job."
For most fiction writers, the day job is a reality that cannot be avoided--at least in the beginning. Some writers manage to land positions as creative writing instructors or English teachers, of course. In these cases, the day job has at least some connection to writing--tangential though it may be.
However, there are only so many of these jobs to go around; and not all writers have the qualifications needed for them (MA in English Literature, MFA, etc.) This means that most aspiring writers end up working inside the trenches of an insurance company or a consumer products marketing firm.
My experience (both personally as well as from my observations of others) is that creative types tend to bristle at the idea of working in a cubicle. And yes, I'm including myself in this category. For one thing, we tend to be hyper-individualistic: we don't like following rules set by others; we don't like bosses; and we can't master office political maneuvering.
The day job certainly has its perils. Nevertheless, the day job does benefit the writer in certain practical ways--and I'm not only talking about the income that the day job provides while the writer is honing his or her craft. The day job also provides numerous story ideas. These should be recognized for the valuable resources that they are, as I explain in this video. Otherwise, you'll eventually find that all of your stories and novels tend to feature a novelist or other creative type as the main character.
In this video, I also describe how my previous "day jobs" provided me with story ideas. I discuss four stories from my recently published short story collection, Hay Moon and Other Stories: Sixteen Modern Tales of Horror and Suspense. Hopefully this video will provide you with a starting point for mining your own day job for fiction material.