Because I saw The Social Network. And it is even better than Zodiac (although there is not very much in common between the two films, The Social Network is probably closer with Fight Club regarding its content).
Everything in the movie is extraordinary. First, a lot of people have said that it was a movie about Facebook, it is, but it is much more. Actually, the only moments the movie really deals with Facebook is in its form, the way David Fincher shot some sequences. For example the opening sequence where the two characters talk with the speed and logic of an internet conversation, going in a lot of digressions but not really addressing each other. Or when Fincher plays with space, windows, walls or screens that should separate the characters, but that his directing renders transparent, as they are in a dematerialised world. If the characters can communicate easily in this world, other directing effects show that they can be separated by invisible barriers, and often the eyesight of characters does not always goes in the direction of the person they are supposed to talk to.
This movie is not only about Facebook because the Social Network of the title is not only Facebook, it is as well about the old establishment of the Massachusetts good society that sends its children to study in Harvard, and about the booming, flashing and casual Start-Up economy in California around Stanford and Palo Alto that has a social network of its own. The movie depicts how these different worlds collided in the early 2000s and how they misunderstood the one the other in a time where time and space was abolished.
The casting is perfect, Justin Timberlake as Sean Parker, the flourishing broke creator of Napster and other sites, sympathetic asshole, Jesse Eisenberg the best kind of autistic billionaire ever filmed, Armie Hammer funny and creepy as a living impersonation of despise as the Winklevoss bros (funny to know there is only one actor, this is a special effect).
The success of the casting is important because the film is not only a social analysis of an economic swift, it is as well a psychological depiction of these strange heroes, with a kind of echo of Orson Welles' Citizen Kane. The movie doesn’t pretend to be exactly accurate about what has happened, things are deliberately added. Another specificity is that it a kind of a variation around the Trial/court movie, except that it is a Transaction movie, which means that the truth is not hat is looked after, it is instead about what are the characters willing to conceal. Very original way to tell a story.
So, virtuoso filming, great screenplay and perfect cast, this is what The Social Network is.