It's effective because it is/was easy for us to forget he is actually a fraud, and must possess a flawed character to prop up a business of at least partial lies. His breakdown of Mob's social life at first seemed out of character, but then again, his vested interests (the exclusive and on-call use of Mob's powers) had never been challenged, so we had no gauge for how Reigen would react to being put on the back-burner himself. It hurt seeing the 'straight man' get deconstructed by a cruel revenge plot and subsequent (normal and social) media circus, but he kinda deserved it. He also got depressed, considered coming clean, and only didn't because, when decision time came, he still had that defiant spark in him that made his life what is was in the first place, and things happened to work out.

I'm unclear, did Mob know he had no psychic powers from the beginning or not?