Why do people buy from you? It boils down to two things: they found you, and they picked you.
Let's talk about "they found you."
To get people to find you, you've got to tell them about yourself or someone else has to tell other people about you. If you're the only grocery store in your town, you don't have a problem with people finding you. You stick a sign outside and reach 100% of your target market.
Most of us, however, spend a lot of brain cycles trying to figure out how to tell the world about our thing. We use ads, content, social media, and so on to try to spread the word.
Moreover, getting someone's attention is becoming increasingly difficult. The amount of stuff being created today—such as photos, tweets, blog posts, Facebook posts, YouTube videos, and emails—is making it hard for our message to squeeze its way into people's limited attention span.
But all of that attention-seeking stuff does have one major thing going for it: Most of it represents communication between people.
As a result, people are more connected to one another, at least loosely, than ever. The effect of that reaching out is really important: The same factors that are making it harder for you to tell other people about your thing are making it easier for people to hear about your thing from someone else.
For that reason, it's crucial to have customers who love what you're doing and who actively spread the word. Some businesses, like the previously mentioned grocery store, can bear the full burden of getting the word out, but, for the large majority of us, we have to acknowledge and embrace that we simply can't do it on our own.