I think an ad model could work if users are segmented based on their interests. What you say on #nostr can tell a lot to advertisers (although it would be for niche advertisers to start) and it wouldn’t require to gather more info than the info already publicly available.

Many folks here are not going to like the idea but I also think that a #crypto on Nostr that would be distributed to #relay owners and would be bought and burnt by advertisers to run ads could be a sound crypto-economic model for Nostr.

Maybe it could be built on a #drivechain?