I find some of your conclusions problematic. Elon wanted to make Twitter less ad-driven and is currently nosediving and can't get out of it. And while a small number of users are gone, Twitter now amplifies extremist opinions that make the echo chamber worse, not better.
- The Fediverse has grown tremendously.
- Meta's Threads is on the path to legitimize ActivityPub.
- People are realizing that social media doesn't have to be ad-driven.
- Twitter has become less of a problematic echo chamber, now that a chunk of it's former userbase is gone.