When promoting a product, a lot of people will first approach friends and family members for support. There is nothing wrong with that but the only way to make the business grow will be to move out of that comfort zone and look farther.
The approach is not that different when doing business over the net because the large customer base will come in the form of an email list.
But how many subscribers are enough to sustain the business? A hundred, a thousand or a million? There is no clear answer but those who have been doing this for a long time know that it takes years to build the customer base. It may take awhile to build it but this just proves that this task is difficult but not impossible.