Assuming there's a problem preventing nostr from winning, why think it's the content? Also, win what?

I'm also wondering whether nostr can scale while maintaining its core feature of censorship-resistance and décentralisation?

It'll be very difficult to compete head on with fiat social networks. Nostr advantage is that it's more than just a social network, and we're only starting to scratch the surface of non-social apps that rely on nostr as their back-end. There's a lot to "win" there...