I think that there was just too much negative association between Facebook's tomfuckery for the last 20 years and the Metaverse. There was no way to divorce the two. Young people didn't want to use it because Facebook is cringe, and old people didn't know how, or couldn't give two shits to learn how, to use it.
That and the Metaverse is using tech that was dated in the early 2000s. There were multiplayer online browser games that I played on as a kid that had better quality than the Metaverse. VRchat is 8 years old and is better in basically every way, and it's VRCHAT.
Long story short, they screwed it from the start by being the ones that made it. It might have worked if it weren't for the company making it.
Edit: Does anyone remember the fashion show they tried to put on in the Metaverse, where they sold crappy dresses for the game for like hundreds of dollars or something? Metaverse was designed to be a blatant and lazy cash grab, and that's why it turned into such an unmitigated cash sink.