Well the truth is unless we KYC all accounts we will never know.
It’s funny, when you built tools to protect against censorship, you also lose a single reference point. The network is no longer homogeneous or has a single truth.
Without getting into ‘what is an active user’, because that has to be defined well first, and is different from current platforms who track reads/logins - what even is a user?
There are lots of bridge bots who rebroadcast content from other networks. They seem like users - but are they? You’d think not, but they appear real in data (ignoring subtleties). Minds broadcasts from their network to Nostr.. it’s real users, just another access method - but users don’t necessarily post Nostr events directly.
You can measure derivatives, like relay active connections, unique posts a day, paid NIP-05, or paid relay users, ZAPs, etc.
It’s late and I don’t claim these numbers are directly meaningful, however I have 17MM events, with very little spam. And I have 100,658 users with > 10 events and a name/display name set. 366,000 with > 1 event (and name/display name).
The Damus Nostr Account has 164,186 followers - and all new app users follow that account by default.
If we legit hit 700,000+ active users four days in a row, I have no idea how.