The thing is that there aren't significant direct production costs per user for technology services like there are for material items, just overall maintenance costs that only scale noticeably with a large increase of new users, so it would actually be possible to pay for infrastructure and salary costs and all of that with just a percentage of your overall userbase being subscribed and subsidizing the rest. This is actually a monetization strategy that's working out for some privacy focused services like ProtonMail. So it would be necessary to convince some users to sign up but not necessarily all of them.