The discussion, and your last questions, pops into my head the thought "there are no bad employees, only bad managers." Not 100% true, but there's something to it.
To summarize the comments above, no one is indispensible unless perceived so by the person who has termination authority. I believe it.
But I firmly believe that it is a very rare bird who makes a really fine manager. Most of us have to suffer through terrible excuses for managers. I think
THAT is the root cause of most bad employee behavior.
I had good one, once, when much younger. I was part of a team of recent grads, frightfully intelligent but not so experienced, who "knew it all" and were part of something really exciting. Our team boss had the personality & savvy to herd this bunch of tempermental cats into some great award-winning achievements. It was the best experience of my career. He quit to go on to much greater things with that guy who ran the "Fruit Computer" company. The company replaced GoodBoss with "YearsOfExperienceManager" and it all went to hell. The entire team quit in a manner of a couple months.
I had the experience of salvaging a "trouble employee". This person was hated by the entire company and the regime wanted her gone, but she was wonderfully competent. I used the soft approach, was patient, and was able to get her to understand she needed to modify her behavior. She did, and the company was better for it.
We're all made in the image of the Almighty and should be treated as such. It rarely happens, unfortunately. For the so-called "trouble employees", if given the opportunity, I would try everything I know to salvage that employee. If unsalvagable, then I would attempt to guide that person into another position and/or company where they could be happier and a better fit. But the "quick reaction, decisive management" culture we live in today, a result of the dysfunctional HR weasels and legal industry, rarely allows that opportunity to treat each other with anything resembling human dignity.
TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering