Best I can tell 2 billion people use Facebook every day.
Either Facebook marketplace has the trade volume of a medium-sized continent or there are way more boomers than you think.
As is often the case with Meta stuff, anglo people and westerners in general tend to think usage works in ways it just doesn't. There are entire parts of the planet where Facebook never died and is THE social network, if not the Internet.
This, and I think Flohmarkt is not enough. Many craftsmen only publish their researches and sell their works on Facebook, for example Adam Bodorics Swordmaker. Their crafts are excellent, but they don't appear anywhere else. The only choice I've made now is sadly just avoid them.
I've been noticing more ads posted up in the neighborhood recently, I feel like people who are off Facebook are looking for new ways to contact those outside their social circles.