Why? Because I've willingly made changes to my personality from INFP to INFJ to ENTP, now closer to ENTJ, simply so I can succeed in different areas in life more efficiently.
The test is self-fulfilling, and I think it's easy to manipulate it to make it say what you want it to say. I think a test isn't good enough, and that objective analysis of one's life, current relationship with family and friends, behavior, etc. needs to take place for a legitimate assessment of what someone's preferred "type" happens to be.
Either way, I can just about mimic any type I damned well pleased to get what I want. After about a month of acting out a type, I simply fall into it and "become it."
The fact that I can reprogram how I behave in a matter of weeks makes this indicator less and less useful as a source of insight to how I act and more as a tool to identify my behavior and manipulate it.
Who else has this problem?