The first thing to remember is – no one is indispensable. If you get hit by a bus tomorrow the company will go on without you. People may have a bit of trouble at first, but new processes will develop and new people will gain expertise just as you have now. Heck the company might be better off in the long run without knowledge bottlenecks.

Second, being indispensable doesn't do a whole lot for job security. If the company is doing well, you need to perform exactly at average to stay employed, no more. And if the company is down in the dumps and there are mass layoffs, who is going to judge how much knowledge you have in your head? All the people who know how good you are are probably getting fired as well.

Third, you are probably not as important as you think you are. Upper management isn't sitting around singing your praises in their weekly meeting. No, they are focused on the rising star who is executing new ideas and launching new product lines. You are meanwhile being taken for granted.

Now, if you are in this position the author writes about, the time to get out of it is now. Realize that no one can help you but yourself. Start redirecting people, or ignore them altogether. Make noise up the management ladder. Play dumb if you have to. Eventually the rest of the company will find some new punching bag and leave you alone.