Facebook may have been invented as a substitute for boredom. Maybe it was born too as a mediocre substitute for true personal relationships within a society scared by real human contacts and by true feelings. Facebook works the way poems, novels and films work: everything seems real; but everything is fake or, if you prefer, it's all about fictional places, fictional feelings, fictional relationships. You are there without never really being there. You feel a lot of things without incurring the danger of being hurt by genuine pain or disaster. At the end of each poem, photo, short story or episode of the novel you are still alone, as lonely as you were before. Nothing happened. Cosa mentale... and then emptiness. You may have visited Dante's paradise (or purgatory or inferno) but you were able to came back from that experience more or less untouched.
At the same time Facebook is about monetizing our feelings, our creative impulses, our thoughts, our energy. Facebook is some sort of second and revised edition of boring life in modern capitalist societies. But it rewards our narcissistic needs: we are in some way a star in a big movie and not just a bored guy spending most of his time alone in an empty apartment or at Starbucks gazing to other bored faces.
The morons that invented Facebook for us morons are making a lot of money with it. We are the human substance of their robotic machinery. It's like making a film without paying the actors because the actors, like rats in the laboratory, apparently move and act spontaneously, unaware or disinterested of their condition and situation.
It could be different if money were not what matters most for the guys who created this perverse machine. I guess that the ones among us that still use Facebook knowing what it is about keep using it because it in some way facilitates without too much formality our relationship with some of our distant friends and acquaintances. If we could keep it for just that minimal service, the danger wouldn't most probably be enormous.