I don't understand how storage can cost a million dollars when they don't store anything. Even if messages are queued, how do you get millions of dollars in queued storage? It's hard for me to imagine... even if you receive and send trillions of messages I don't think you would end up storing much at all.

As for registration fees, it sounds like they should use authenticator instead of SMS... and stop requiring a phone number to sign up. That is why I left Signal (went with Matrix). I don't see why anyone would want to tie their Signal to a phone. If you value privacy, why would you do that?

Servers cost seems excessive as well. I don't believe you need that many servers, even if you served a boat load of requests.

As for bandwidth.. okay, that may be the case. I am not sure how you can get that cost down.