How do you think Nostr can improve payments? Are you thinking along the lines of NWC and adding a ID/messaging layer to Lightning payments?
The amount of backend stuff for various systems that Nostr can improve is immense.
Decentralized social media is a big deal, but that use case goes up against very large existing network effects. If you judge Nostr’s success based on not gaining traction on that front quickly enough, you’ll likely be disappointed. That’s why a lot of people come to Nostr, post a bit, and then leave for a while, and then come back when there’s some sort of catalyst, post a bit, and then leave again. That’s fine. It’ll take time. It’s a slow burn.
But in the meantime, the amount of development going on under the hood for all sorts of things is huge. In particular, I think the open-source social graph aspect is under-appreciated for how important it can be beyond just socials. Payments being the next obvious one, and probably bigger than people think. And many other things.
https://pippellia.com/pippellia/Social+Graph/Navigating+the+social+graph 
Discussion
Basically, I don’t see why I would use any new wallet that doesn’t have a social graph of some sort attached to it. Nostr happens to be a great open source social graph.
If I can’t look up people from within the wallet and pay them, then that adds friction. Payments and social inherently work well together, even if I was not interested in actively posting on social media per se.
I hope to see Nostr integrated into gaming soon. I dont know exactly what that look like but players can actually own their game accounts and transact p2p.
I think nostr would work great for chess-by-mail type games, as well as for server browsers/matchmaking.
The social graph is a really cool element but I think you’ll enjoy this talk from a recent Nostrasia if you haven’t already - seems like it will also enable crazy use cases impossible on fiat rails!