Who even supports FB?
The media? No, they hate them because they took all their ad revenue.
Republicans? No, they hate them for the censorship controversy that happened a year or so ago, and because it is full of ultra left wing silicon Valley types.
Democrats? No, they hate them for the whole Cambridge analytica, Russian data thing.
Facebook has made a lot of enemies, and there really isn't any sort of constituency that SUPPORTS them.
So, even if a business currently gets a lot of revenue from Facebook, as long as a business thinks that other businesses in their field are more dependent on Facebook than they themselves are, they should be fine with Facebook declining.
1. Money
2. The fact that they are the only source of information that a good percentage of the world uses.
Money can be used to buy power, and they already have a not-insignificant level of control over the flow of information (which is power itself).