I stopped using Facebook about one year ago, when I started to feel like 80% of my friends and acquaintances where not able to distinguish between fabrications and reality, when I started to have rage attacks every time someone would sent a chain post, which means when I started to have quasi epileptic attacks several times a day, when people would not recognize the gap between the cheap quality of the "quote" shared and the writer it was being attributed to. That was the last thing that really pissed me off. Someone created a v-card with a deist aphorism, very poorly written, and signed it "Jorge Luis Borges". It was resent hundred of thousands of times.
The last time I signed up was last year on my birthday, to thank for all the messages and to let everyone know that I would not be back there again ever. I still receive emails from FB letting me know I have notifications. I just ignore them.