Although we like to think that our software testing work is unreplaceable, we will present to you hard true, everybody is replaceable. The post is based on a remarkable book written by Chad Fowler, The Passionate Programmer.
During the bad days of software testing, we all think that if we quit just now, the whole company will collapse. Well, this is not true. Software testers leave daily, and companies do not bankrupt because of that actions. Everybody is replaceable.
On the other spectrum, there are software testers that try to make them not replaceable in an artificial way. For example, they do not share knowledge, they do not document their work and procedures. This is contra-productive. You will create a hostile working environment and make a manager take some actions. Maybe the manager would move you to another project or will simply fire you. Do not do that, or you will be recognized as the creator of a hostile environment.