Initial traction on nostr shouldn't require money.
The introductions hashtag should work but it's held back by spam. I think people don't scroll through it more because it's unpleasant trying to figure out if the posts are from real people or not.
It would be really good to have a project where new users can actually meet with an existing nostr user in their area to prove they're human and get into a "web of humans" where it's easier to get traction.
The project could have a main npub that follows a list of trusted users to repost/introduce every new verified human, until growth gets too fast to keep up with. Maybe it could be automated and never fail to keep up.
On a future version of nostr, the "web of humans" would be based on web-of-trust profile tags, and the main npub reposting newly verified users would become outdated. This tag-based "web of humans" has little to do with this project, it should happen eventually whether or not a project like this ever does.