From what I've read, Meta's strategy (and valuation) ultimately relies on 'ubiquity' (as they put it) - where everyone on earth has a Meta account and uses it. The stall in user growth is accompanied by a massive decrease in the company's valuation as a result of this, so they do the classic "what's working for the competition" action.

I've not had a FB account for years, and didn't use it other than for messenger for years before that, but when I was on there, I felt that most of their growth came from 'copy what other sites are doing, extinguish the competition by doing this' strategy, as everyone is on facebook anyway. It's worked for them so far, just now it's a bigger shift to try to emulate TikTok rather than try to destroy local ads sites or small business site hosting.