It is at the intersection of pornography and parasocial online relationships (seen in Youtube, Twitch and other influencers), both extremely profitable. Looking at some of the revenue breakdowns the fees to message are just as significant as subscription costs.

On average I don't think it is particularly healthy to replace real social/ sexual relationships with parasocial ones and I think that is the primary use for these services. For the most part they lack real meaningful intimacy which is a significant benefit that real relationships provide. I don't think many who maintain healthy social and romantic relationships are the majority of users of the platform.