[webwright]

Startups are often about finding money machines. Ideally these guys are constantly asking questions like:

1) What is the lifetime value of a user? 2) What is the lifetime value of a property owner who lists with us?

Once you start to be able to define the LTV of various user types, you then look for way to trade money for users/customers. If a property owner statistically averages $1000 in profit for airbnb over 3 years, you'd be willing to buy a user like that for <$999, right? Not so fast, though. $999 is a lot of $ and 3 years is a long time. Funding like this allows Airbnb to "buy users" (thru paid channels, growth teams, etc) at a rate that would be impossible with just organic revenues/profits.

In short, imagine businesses as an engine where you put $1, and (hopefully) $1.25 comes out. Young businesses don't often have enough cash to fully take advantage of the engine they've built.