Men may come and men may go but I go on forever. I remember this what I read in my class X. So if somebody thinks that the organisation will stop if he is not there, I say he is foolish. You may be good at your work and you might have left your mark on the happenings in the Organisation. But when you are not there somebody else will take care and see that the system will run. Nobody is indispensable in this world. This is the fact and the person who realised this fact is the Wiseman.
In a good sense, many sincere employees worry about taking leave doubting about how work will go in their absence but once they go on leave, work goes on may be at a variable level of quality and efficiency. Such thoughts should not be encouraged, especially within a team as it would have an adverse impact of the others and the productivity.