I'm really worried that if Twitter becomes unusable that I won't be able to stay afloat financially.

My main source of income comes from newsletter subscriptions (https://www.readtpa.com), and Twitter has been the biggest driver of new free and paid sign ups.

I don't know what to do, to be honest.

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And I'm not alone in that. There are a lot of independent writers, journalists, content creators, etc., who have relied on Twitter to promote their work.and Twitter was already a difficult place to be. It wasn't some sort of bubble of positivity or lefty groupthink (as EM keeps trying to frame it), but now it seems like he's actively trying to push progressives off the platform.
It's why my most recent newsletter(my weekly recap) included to many links to other people's recently launched newsletters: I want to help as many people as possible.
Anyway, it's really difficult. There are no good options or answers for people in this position.
@parkermolloy Nevertheless, Musk's Twitter is past the point of no return. Those with big followings there need to leave a pinned "where to find me" tweet and focus on developing followings in other places. People who aren't authoritarian bigoted fascists are going to moving, "stay and fight" won't work, soon Musk will be tweaking things to take away your "freedom of reach", as he calls it.