You may have heard of the Imposter Syndrome. This phenomenon was first described in 1978 by clinical psychologists Patricia Clance and Suzanne Imes. It´s characteristic is a constant feeling of the lack of legitimacy and competence required to perform one's job. This feeling is accompanied by a sense of deception and the impression that, sooner rather than later, this lack of legitimacy will be exposed.
Its modus operandi is a negative cycle that tends to get stronger: