Yeah, that's what i meant, Linux Software Foundation is a non-profit organization too. I can assure you they are paying more than Signal just for their infrastructure. For testing purposes, releases etc. I don't even know, how many Engineer's do they have, it's huge, like interestingly huge.
My point was, both are non-profit organizations. As far as i seen this sounds quite interesting to some people but this is what many highly successful companies income model.