There's a debate in startups whether you should build your product or community first. The thinking is that if you have a community, then you will already have people ready to use your product when it ships. There are examples of that method working, but there are more examples of it not working. Having a community doesn't guarantee that people inside or outside of it will ever want your product.
The shortest answer is doing the thing. If you want to build a community, do it. If you want to build a product, do it. If you want to build both, just do it.
At Gum, I wanted to build a community product for startup founders, so we are building our product and community in parallel. It's a good design approach because our earliest believers are helping us shape our product into something that they want, use, and buy. Now, we can continue iterating on our product to serve the people in our community and scale it to other startup founders.