The answer to your second point is simple.

Meta’s properties (FB, Insta) have something that most other social networks are lacking: A network of real-world family and friends.

Twitter, Reddit, Mastodon, Lemmy, Tiktok, and the rest all tend to have communities built from the platform’s population, based on shared interests. Meanwhile, FB is the platform that you use to connect with your oddball uncle and high school friends from way back. That’s the sunk cost that makes it so much harder to leave than the strangers on reddit who share your love of lime jello.