Air b and b doesn't have to worry about the normal costs that most businesses do in serving their customers, because they're not the supplier of the product. Unlike a fulfilment base business like amazon, which literally has to ship physical goods everywhere across the world, air b and b is built on the internet. The third and final characteristic of an aggregator are network effects. And if you want a full deep dive on network effects, you should check out the recent founder's journal identa on the topic. It was dedicated to network effects as a business strategy.