Secure DMs and groups might be how Nostr wins. Like Signal, but better: no phone number or centralized service provider needed. Actually there are no publicly visible user IDs involved, so in that regard it's similar to simplex.chat.

Unlike public messaging, DMs do not depend on the network effect. Great for onboarding people and keeping them returning with push notifications. They get a bitcoin wallet, zaps and all the other Nostr greatness on the side.

Many people don't want to let go of their existing follower base on X, but "Nostr DMs only" is easier to do. I could imagine that becoming a thing in the Bitcoin scene at first.