Part of the low numbers is probably due to core ideological positions of the tech due to the bias of those who create it. I tend to agree with those positions, but most of society simply isn't there yet, which is why I'm softer on people who still choose to use other platforms even if I'm Nostr only.
Thinking back to when I chose to go onto Facebook, Instagram and Twitter (many moons ago 🤢🤮), I went because the platforms felt agnostic. It was just a place for all people to gather (before everything went crazy) around virtually any interest, topic, or relationship.
Nostr feels a lot less agnostic when you get here. You're basically water boarded with Bitcoin and Nostr. And you really have to work hard to find the stuff outside that, at least from what I remember as a noob coming into the popular clients. Maybe it's improved. I doubt it. Follow packs are one thing that give people hope that things will as far as onboarding goes. But even when I search out people in other communities (music, art, etc) those people are still typically hard tied to Nostr and Bitcoin. Other topics exist mostly on a technicality from what I've seen. I've tried onboarding normies and they have no interest.
I wish I could offer solutions to my perceived issues. But all I can come up with is we have to attract creators from outside our little echo chamber. It's a hard problem that will likely be solved with time. I've tried to get my favorite creators here and their concern usually is lack of an audience. I think pain is a great motivator, so I'm pushing hard when creators experience demonetization and things like that. They could simply cross post here and add a link and mention it in their other posts. I recently started selling the least effort approach to my people, but I'm just one dude.