What all of this points out is that Facebook never really solved the "MySpace/Friendster" problem, they just had the better product at the right time and were able to get a few more years of safety by acquiring threats (which is not a long term strategy).

It's wild that FB has become such a highly valued company despite the fact that they have always been resting on rather shaky foundations.

We can also start to see Goodhart's Law in action at scale. Running your company by constantly optimizing for metrics (as so many startups mimic now) eventually does catch up to you. The vitriolic content that initially got them massive engagement eventually gets more and more people repulsed by the service.

In the end, just like MySpace and Friendster, there is nothing that really prevents users from exiting from the platform extremely fast once the tide of the network effect turns the other way.