So, save the hot air for someone else.
Right because 900 Million accounts would stop all at once and no one would notice. (that is equal to almost 1\7th of the population of the entire planet) 100's of Millions in ads and not to mention the online commerce that takes place on FB would seek to exist and no one would notice.
I think I've figured your problem out.
Its simple. You haven't a clue about any of this.