I can say, as a now self-published author, that it does…a little bit. It’s better than nothing. I know some self-published authors who have published and then started building an author platform. I see how distant it feels when going to their pages and stuff. It looks and feels empty and as if they’re calling out to the void.
And also, I want to add, I think “building author platform” looks different for everyone. To some, that’s a lot of marketing to readers and telling them what genres you write and what kinds of stories you write, giving short stories out for free, etc. To others, that’s building friendly connections with readers that like to read the same stuff you like to read.
So, I said that it’s better than nothing and that it does help to have a platform. As for me, I’m consistent (sunset gradient palette, the fox, books), and I have connections especially on Instagram, so I think I have a platform.
As for marketing, if I have to think about what people want, I’m going to stress myself out. So, I decided to take the “self-serving” route. My perspective on marketing is just me sharing the cool things I made. I’ve always found pleasure in sharing the stuff I created whether that’s a book I wrote, a cover I made, or a drawing I did, I want to share the stuff that I’m happy with and I’ll do it in the way that makes me happy.
If other people look at that and feel happy, well, that’s good enough for me. If they take a step further and actually buy something I made, well, that’s a plus.
My first book published in October. For an indie author, that’s too soon to be able to tell if anything is working, so I’m going to continue to tap people on the shoulder to show them the cool stuff I made until someone turns around to listen 
Yes, it does require money and you do have to treat it like a business, but to what extent is all up to the indie author. I’ve decided for my own mental stress sake that I’m only going to do as much that is still fun for me. If I find myself stressing than it’s time to stop and make it fun.
For example, I got tired of saying “here’s the blurb for Between Roses!” so I decided to write a funny blurb, and then a crazy blurb. Idk if any potential readers found those and took interest. But it was fun for me.
I also learned that if you are your own business, it’s important to pace yourself and also it’s important to know that you CAN pace yourself. There’s no outside force (like a publisher) expecting you to market your book (just because you have a publisher, doesn’t mean no marketing).
As a self-published author, you don’t even have to do any marketing if you don’t want to although you might be missing potential readers. You can throw your arms up and say, “I’ve had enough of that for now.” Despite the costs, it was all worth it once I got through a few learning curves. The learning curves were a mental cost I was willing to pay to become a self-published author because I knew once I did it once, it would be that much easier the second time.
I feel like I was a bit all over the place with my thoughts. Any questions?