The Facebook app itself is massive, it's the most used classifieds, basically replacing craigslist, still used for many groups and many local businesses use it solely, their ad business is still raking it in. Event coordination and connections are maintained on FB since most everyone has it.

Instagram isn't dying either, it's very popular for both advertisers and influencers, TikTok stole some but they are really two different services, one static images one short videos with some overlap to compete.

Your social circle may not use those apps but A LOT of people do.

I don't use any social media because I'm not social, but I have to use FB to see community updates, to coordinate with groups, to sell/buy things, to lookup businesses without websites, etc. I don't see TikTok or others having that moat or even attempting to dig it.

Facebook has the businesses, the users, and the developers. In no way are they dying.