I wrote about this in my book "Influences and Influencers". It is about knowing your importance.

We are all place holders. We do not own any job or position. We hold that place until we leave and when we do, someone else will take the role and move it forward.

I worked in three companies in my life. After I left each, amazingly, each company continued on without me. That includes my last, the one I helped to found.

Please remember that when you think you are indispensable. You are not. Just do the best you can do in the time you are there. And then leave it in great shape for the one to follow you.