It's possible that they are uncertain about the path to monetisation. As far as I see, it's either subscriptions or selling ads.

Their uncertainty is magnified on the outside tbh. e.g. There are other things at play that can (probably will) cost a lot of money. The protocol (ATProto) they’re developing and advocating as a “platform”.

Say I’m building a cool app around that, how do I plan how much is this going to cost me and can I stomach the risk of binding myself to this “supposedly open” platform without knowing how it will work in 6 months?