Let me compare facebook from one of their biggest competitor years ago which is friendster. I can still remember the time when I was more addicted to friendster than fb because I find facebook boring since you cannot change the design for your profile, you have no choice but to suffer from it plain theme. Then later on, they released Farmville and other games which I think made a big difference and many users switched from frienster to facebook(including I, lol).
Up to now, they keep improving their app versions(facebook and messenger). Who wouldve imagine that even sending money through messenger now is possible. I think Facebook’s secret is that they keep adding feature that will be very useful for their users, and that alone will attract people to stick by them.
