People can also derive meaning from their work and feel that it's essential, while in reality it might make very little difference if they show up on Monday.

Personally I'm fairly sure there's a large number of "bullshit jobs" and I have my own, unfounded, opinions regarding which jobs that might be. I'm just not convinced that we can identify these jobs by asking those who work in those position.

There's also the jobs that truly are essential, but only because something somewhere else is broken.