When I was a senior in college, I was working full time and going to school full time. My work schedule was afternoons Monday-Friday, and mornings on Saturday. I lost some sleep, but it was worth it, as the job was in my chosen field. My boss (who was also in her 20s) was kind of a hard-bottom, and we had some conflicts, but I chalk that up to differing expectations on both our parts.
But the one incident I've never quite forgiven her for, 30-plus years later, was her reaction to my father's death. My mother called on a Monday to tell me he had passed. Of course I promised to come home the next day. I called my boss and told her what had happened. She told me I could have the day of the funeral, the day before and the day after off.
I arrived home Tuesday to discover that the funeral was on Saturday with calling hours on Thursday and Friday (fairly standard Catholic tradition in that time and place), according to the arrangements my mother and older siblings had made -- without me, but that's another story. I called my boss to tell her I couldn't be back until Monday. Her response, in a very snotty tone: "Well, I hope you realize what this is doing to my schedule!"
Plus, I got a ration from mom and siblings for my mildly panicked reaction to learning the arrangements and realizing I would have to take more time off than I'd been authorized for. How selfish of me!
A couple of years later, the founder/CEO of the small company I was working for actually declared, "An ounce of loyalty is worth a pound of cleverness." (Translation: Take that, you people who don't like the way I do things but think I won't replace you because your job skills are too valuable!). This prompted a co-worker to quip that she was thinking about naming her dog (Company Name), because "he's not clever, but he's loyal!"