I think FB turned the corner when Mark stopped driving his Acura. I'm not sure when I last saw it at building 16, but that was the date for me.
The change happened because FB didn't internalize quickly or deeply enough that the mindset that got them to defeat MySpace wasn't the mindset they needed to become a trusted service for the long-term. Obviously yes it still exists but it's an absolute shell of what it could have been had this not been squandered -- which is the point that the parent comment was addressing.
Almost like a "I don't owe, but I should pay more, but I don't owe..." thought process that leads to moral vapor lock.
I think there used to be more release valves for this pressure. There aren't any tithing billionaires, for example.