> That $3/month figure actually makes me more concerned. Sure it's low for a business with revenue but donation funded services rarely get donations from more than a few percent of their users

That's way, way lower than most other services, including most messaging services.

And donations aren't Signal's only source of revenue. Over a third comes from other sources.

> So Signal probably needs something like $30-40/month from people who actually donate, which seems unlikely.

Well, they broke even last year, so apparently it does work out.