Such feelings are widely prevalent (one estimate is 70% of the population), especially in professional groups--talented, high-achievers like doctors, entrepreneurs, CEOs, teachers, managers, university professors.
My conclusion from reviewing these articles (see image): The prevalence points to a cultural issue rather than a "syndrome" which implies disorder or dysfunction. In our society we value knowing the answer and taking action. Yet, issues we tackle today usually have no easy answers and we need to experiment and learn from failures. It is not surprising that imposter feelings would commonly arise out of this discrepancy.
I like what the scholar Stephen Brookfield says:"I wouldn't want to work with anyone who did not have some feelings of impostership, who didn't feel a sense of struggling in the dark, of trying to draw meaning from contradictory and often opaque experiences. To feel this is to open up permanent possibilities for change and development in our practice." (Stephen Brookfield, Becoming a Critically Reflective Teacher Jossey-Bass, 1995)
Brookfield says the way to deal with the imposter syndrome is to talk about it--"Once impostership is named as an everyday experience, it loses much of its power."