Every writer is different. For me my job was wonderful, all 40+ years of it. Most of the time I worked on projects which once were sci-fi: deep-space explorers, fighter jets, laser weapons, etc.
I also met some impressive people, scientists, engineers, administrators, soldiers, pilots, a couple of astronauts. I got to know their human as well as professional side, the joys and sorrows that most of us share. That is the core of all stories: people.
In the process I learned skills and disciplines, big and small, that I use every day as a writer. There was no writing on the job: my work was as fascinating and engaging as the stories I created in the evenings and weekends. It was because I could and did commit myself fully to my day job that I learned how to do the same at my new day job: full-time writer.
So instead of grumbling about your day job, embrace it. Volunteer for tasks which will serve you as a writer, get to know a wide range of people, and make sure you sock away pensions and investments to help you in the first lean years when you finally do get that dream job: full-time writer.