I tend to think Facebook is more like a slot machine than anything else, where you are constantly putting in something of value (your posts, pics, etc) in hopes of getting something of greater value back (likes/shares, friend requests, heated debates, etc).

And just like a Slot Machine you are always left wanting to come back to play some more and even if you do your best to quit facebook, you are always being constantly reminded that of its existence everywhere you go.