Being irreplaceable and indispensable are not the same thing. While you can become indispensable in terms of your value, you are still not irreplaceable. Having a goal of being irreplaceable so that “your existence alone benefits the company” is the fastest way to become dispensable. Why? Because most smart organizations don’t rely on hero’s, but develop many people to all be top performers. An indispensable leader develops other leaders. An indispensable employee is a person who contributes to the success of his or her team. An indispensable middle manager not only supports his or her department, but other departments as well. Your value to others is based on your contribution to others success rather than the Me-Centered approach of most people trying to be irreplaceable.
Yes, you may lose your job, and that is a horrible experience – I know from my own experience of what it is like to be unemployed. However, when you know your strengths, and are willing to serve, even when you are out of work, you can maintain your self-esteem and confidence. I did more volunteering when I was out of work, because I didn’t want to sit at home in my discouragement. I thought, “let me be of service to anyone who I could help.” That is when I made myself indispensable and discovered the power of making myself indispensable rather than irreplaceable.

I remember my experience between working with leaders who developed other leaders and those who didn’t. I found the former much more enjoyable to work with and the latter much less enjoyable to work for. I also learned more and was more dedicated to those I worked with instead of working for.
I also found, though that was not my intention, the two times I was out of work and volunteered my time that they both led to new jobs.