>>mikece+(OP)
Signal had 40 million active users in 2021 [1]. With 14 million in infra cost, that comes to .35 per user/year. Total expenses are about 33 million, so about .825 per user/year. All in all that seems very reasonable.
>>umanwi+9z
I encourage you to read the article, but Signal minimizes the metadata it stores about you, doesn't hold on to you contact list, doesn't keep information about your IP address, etc.
WhatsApp instead makes tons of money from this kind of metadata.