Unless someone is faking symptoms for a particular outcome - like pretending they are insane so they get a lesser sentence in a mental hospital instead of going to jail (which, to go off on another tangent, could possibly indicate psychopathy) - then they are likely doing it for attention. That extreme need for attention comes from somewhere - probably from having unmet needs in childhood - like so much other stuff does. I think that the faking of psychological problems in itself would be indicative of a need for psychological treatment, anyway. It's kind of like they're just making their issues more visible - whether consciously or not.

But then isn't there also 'psychosomatic' pain? It's still not 'real' in the sense it can be found in a test, but it is 'real' to the person, they're not 'faking' it.