Is growing an audience worth it?

So, I've been working on growing a personal audience because that seems to be the thing to do. I understand that the idea here is that you build an audience by providing free value and eventually in the future you leverage that audience to drive traffic / be initial users of some offering in the future.

I've been able to grow my audience pretty quickly. I'm currently making content on Swift & iOS Development, though my interest is in building things and being a maker instead of a particular technology/language.

I'd love to hear some stories about people that grew audiences and the benefits that came from it and how large they need to be to start seeing "results".

I just feel like I don't have a clear idea of why I'm doing this in the first place and am curious about what inspired others.

I think I'm sort of just blindly hoping that it'll be useful in the future. Marketing isn't a strength of mine, so it seemed trying to build an audience couldn't hurt.

What happens if my audience is not in the same niche as the SaaS I potentially start in the future? Isn't it a big waste of time then?