[smeyer]

Are you asking how airbnb could have spent money to attract users? For example, they could have spent money to provide a discount (charge the guest $100, pay the host $200, both are more likely to join than at a market rate of $150). Also, they could have acquired hosts by offering a guarantee, such as paying for 3 nights a month if they don't have at least 3 nights worth of guests. There are also more general techniques like advertisements and salespeople and such.