This trope is popular in Philosophy. One such thought-experiment goes like this:
Bert is mildly socially impaired: He just doesn't get sarcasm. During his entire childhood, he is everybody's laughingstock, but he mistakenly believes that they are laughing with him rather than at him.
- He fails to see that everyone around him is simply in it For the Evulz, he incorrectly believes he has friends who actually care about him.
- As he reaches adulthood, some of his "friends" become powerful and decide to carry on the charade. Bert now believes himself to be a respected coworker who contributes to the company, but no one really regards him as a peer. His only real function in the company is that he'll be an expendable scapegoat if something goes horribly wrong. Luckily for him, the company never ends up having to discard him.
- During a trip to a third world country, one of his "friends" befriends a prostitute. Their friendship is real, with mutual affection, and she quickly joins Bert's circle of friends who laugh at him behind his back. They want their new friend to gain Western citizenship, and Bert becomes a convenient tool for that. Thus he gets married to a woman who doesn't care about him and never will, but who will let him believe that she does. She even lets him have sex with her a few times... especially after she gets pregnant, so he will believe that the kids are his own.
- "His" children grow up to pity him, and they are grateful when they find out that the "uncle" they like so much more than him (and who their mother truly loves) is actually their real father. Of course, they are too polite to tell Bert the truth.
- As Bert lives out his life, he dies surrounded by people he believes to be his friends, a woman he believes to be his loving wife, and children he believes to be his own. It's all a lie, and afterwards none of them have time to go to his funeral since they happen to get invited to a party that is held the same night. He has outlived his usefulness, and nobody really misses him. On the contrary, they merely feel relieved that he can no longer embarrass them by exposing any of the stuff they used him for.
And the question is: Did Bert live a good life?