I use Facebook to talk to about a dozen or so people I wouldn't otherwise. I know, because I dropped off for a couple years and didn't really connect with them, which sucked.
But on a day to day basis? It's the absolute worst dregs of boomer humor and low effort, brick stupid content. It took a long time to screen out the political garbage I hate and slowly unfollow the various people who've gone insane in the past 8 years. I was left with like ... purposefully bad cooking videos, advertisements, the occasional comic book page (why?!?), more advertisements, old/bad memes, more advertisements, and most important of all, advertisements.
In fairness my wife uses it to coordinate with other parents from our kids school. Why we can't use something else to do that coordination I don't know, but eh.
tldr: It's for older millenials on up and mostly garbage algo promoted content thoroughly seasoned with advertising.