Michael Lambert: In adults who enter treatment, the rate is about 5–10 percent. In children and adolescents who seek treatment, the rate is about 15–25 percent. So it's relatively rare in adults but all too common in children. And the major causes are external events that set people back like a divorce or a death or loss of a job, so it's environmental. And then within the therapy itself, it's usually related to some kind of rejection that the person experiences while they are working with their therapist. It's usually not related to specific therapy techniques but to relationship factors where the patient feels misunderstood, uncared for, or neglected in some way.

Oh man, such delusion. 5-10 percent of adults... i bet it's 3x times that at least, especially if you include long term therapy that sucks the client's resources dry and wastes years of their life, or that leaves the client just a bit more hopeless or dejected for having paid someone to llisten to their misery.

Notice how he pins failure on changes in the client's life as the main cause, then mentions the possiblity of therapy being the problem. He also uses dodgy language... the client "experiences" rejection. Most likely the client was rejected or humiliated in some way.