We estimate that by 2025, Signal will require approximately $50 million dollars a year to operate—and this is very lean compared to other popular messaging apps that don’t respect your privacy.
The costs are distributed as there is not one single instance. Just like with Lemmy.
Although there is one huge instance on matrix (matrix.org), a bit like lemmy.ml here. But it doesn’t have to be like that, they can close signups or discourage them similar to the way lemmy.ml is doing that now.