Many people think that no-one could do the work they do within their company. They think they are irreplaceable or that they must keep up with their fellow staff. No going home early, especially when they come in late. That's why people are working overtime and do work that's not part of their work.
There is two reason of this. One is that all the other colleagues think exactly the same things and kill time until it seem to be acceptable to leave work. Two is that often fear of loosing your job covibrates. Fear your boss, of loosing your job, of what others might think. Both unfavorable attitudes, because you are needlessly dependent. No job in the world is worth you feeling bad.
Fact is, if you don't do the job, somebody else would. Not exactly the same way, but probably also good.
So if you as a person are not a necessity for any job in the world, for what are you a necessity then? The project of your life. That is something you can design the way you like.