@a There are 18m people trapped on Bluesky by the collective action problem and Bluesky's ongoing foot-dragging on federation. Raising money to create federated servers for BS lets those users escape should Bluesky's management turn sour, and also puts BS's investors on notice that if they order management to enshittify the service, they'll hemorrhage users.
https://pluralistic.net/2022/10/29/how-to-leave-dying-social-media-platforms/