i agree but this quiz is as professional as me making a quiz that determines you clinically insane if you choose apple over orange.
Self-assessments are used in psychological studies, and developed by psychologists. Not every personality quiz is a bunch of arbitrary twaddle someone wrote up one evening out of boredom. The results are based on averages, it's just a preliminary indication. It won't tell you you're a narcissist, but it can tell if you if you tend to answer the way narcissists do.
Just because it has a lot of potential error from the subject and doesn't provide a conclusive result on its own doesn't mean it's unprofessional or unscientific.
The questions clearly have to do with narcissistic tendencies, not "apples and oranges."
Poll