Also Facebook completely blew its original "what are my friends doing?" market. Very few people use it for that anymore.
It still has some value - Groups and Marketplace are pretty popular, and a decent number of businesses use it as their website. But it doesn't really have the "all my friends use Facebook" moat anymore. That's moved to Whatsapp (at least in the UK).
(And yeah Meta own's Whatsapp too, but Whatsapp is not really monetised at all.)