Bacause FB/Meta and none of it's other incarnations is not fashionable among young generation anymore, it's platform for old people.
I'm wondering what kind of play would be successful long-term in this scenario with long-lasting social platform to capture next generation which is naturally inclined to be in opposition when it comes to parents way of life. Maybe creating some kind of "undercover" division not officially connected to parent company? Or even spinning it as some part of company "revolting" against main body and going "rogue". But in both cases mainly founding would uncover the plot.
Of course buying competitors usually works too to some degree - or at least allows to buy some time.