There are parallels between Facebook and Microsoft. Both came up with a concept that quickly became ubiquitous. People use Facebook for the same reason they use Microsoft. It is there and everyone else is using it. Ten and twenty years ago, people were predicting the demise of Microsoft. Apple would win out. Open source would win out. But people are still on Windows and paying for Word, Excel, etc. Both Facebook and Microsoft reached a point where it did not matter whether a rival had a product that was better. The improvements in the rival product were not worth the bother of trying to use the rival's product.
Facebook's problem is that it spent all its time developing VR crap that only has a very small niche market among techie types and gamers while Tik Tok out flanked Facebook by delivering an addictive platform that has a broad appeal. But Tik Tok is not a replacement for Facebook. It just chips away at people's attention kind of in the same way the shift from PCs to tables/smart phones didn't mean the end of PCs.
The problem then is that investors are generally ok with Microsoft's stasis but think that stasis in social media is death. It isn't. Facebook has been around long enough now that there are going to be substantial numbers of people who grow old with it and do not want to try the next new thing. Young people will be on it because their parents/family are on it.
Facebook's Meta concept is an attempt to merge all social media, gaming, online junk into one thing. That sounds great in a conference call to investors, but I do not think that anyone wants that or need it. People like moving from one flavor of social media to the next. People who were on Tumblr quickly took to insta. People doing vines found a new home in Tik Tok. People will pick up apps like Slack when they need it. But Facebook will be like the landline in your house. It will always be there even if you do not use it like you did twenty years ago.