The magic of ecommerce is that it allows a retail entrepreneur to launch a virtual store that would have failed as a brick and mortar space. For example, livingstonepillow.com is a site that sells pillows shaped like pebbles. This is an idea that only appeals to 0.01% of US shoppers–
It would be silly to open a retail store for this product because only 2 people in a 10-mile radius would be interested in buying what livingstonepillow.com sells. But online this 0.01% could be a nice audience size for a niche business because 0.01% works out to 32,000 people.