I'm sorry, but what? Nostr doesn't need to sell your data because it's already out there for free out in the public. Everything you post, comment, like, boost, etc is sent out into the public for anyone to compile a prifile of your interests, etc for free. All they have to do is listen to the relays and filter by your npub.

No sade to Nostr, it's literally the best, but let's not kid ourselves about privacy.