I agree that the currently altruistic relays aren't sustainable, they won't be able to store all the data for everyone for free with growing userbase. However I don't think nostr is doomed. But I think the end game has to be some kind of payed model if you wan't all your social history to be stored. Or all users storing their own data, acting as "mini relays", though I don't know if this is technically feasible.
What do you think?
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