I'm curious what the breakdown of donations is. I only have 1 contact with a $10/month and 1 with a $5/month badge. Of course there could be others not displaying the badge. Signal really needs 500,000 people giving $20/month and plus the rich guys giving some millions on top of that to be in a safe financial position.
Maybe something that could be done to encourage donations is have the client estimate how much raw infra costs your usage created and display in the donation screen.
Given that Signal is free as a service, supporting federation only increases their expenses.
Element can do it for their Matrix servers. Process.one can do it for ejabberd. Prosody as well. Why can't Signal?
They've talked about this, a lot.
The internet would be a lot more efficient and able to evolve if we just had it controlled by one single entity like Google or Microsoft. Do you think is a good idea to do that?
The economy would be a lot more efficient and allocation of resources could be a lot more fair if we could put it all in the hands of one single corporation or government. Do you think it's a good idea to do that?
Agricultural output would improve significantly if all crops used the exact same genetic strain and if all soil was artificially managed. Do you think it's a good idea to do that?
In case you are wondering, "ability to quickly roll out post-quantum key exchange" is waaaaay down the list of my worries compared to "facing a catastrophic Black Swan affecting all of the world's communications".
There's plenty of diversity in the messaging space. Decide your values, choose your compromises, pick your platform. Simple.