If the owners are separate from the users, it's not set up for sustainability. If someone other than the users bear the risk of loss and upside of profits, it creates weird incentives whether you want it to or not.
Have you considered running it as a co-op? Every user has an equal stake in costs and profits and an equal voice in decisions. This model literally grows with its users, and it's the only one that does so.
I like this but it sounds like you've chosen the wrong model for running it. If I was going to use something like this (which I would like to, I think, if nothing else to share updates with families/close friends) I would want to own it equally with the other users.