2. Counsellors identify psychopaths based on a pattern of actions that lack empathy. A psychopath might be very "nice" when he meets you, but as soon as he can benefit by throwing you under the bus, he does so with no display of remorse. The lack of empathy is the defining characteristic of the psychopath--a non-psychopath will refrain from throwing someone under the bus because they empathize with that person. Steve Jobs fucked over his colleagues without remorse. Woz then gave them all money because Woz felt bad--Woz showed that he has empathy. Jobs showed he does not. This is why psychologists consider Jobs an obvious case of a psychopath.
3. Vulnerable people discover psychopaths due to the classic psychopath turn. When at a moment's notice the person you thought was so nice to you turns on you and you realize they were just using you. When they "turn" they go back on promises, they throw you under the bus, backstab you, generally fuck you over. Usually they do this by getting you to trust them first because they seemed so nice that you trusted them. This happens ALL THE TIME in the tech industry and if pg isn't aware of these cases he is willfully ignorant.