Some of the ways to burn cash:
(1) Expand operations: hiring people, hiring external services, leasing offices, leasing capacity, etc. All that happens far before any additional revenue comes in.
(2) Capex: capital expenses (buying servers, equipment, etc.) require cold, hard cash (or debt, which "costs" more than equity for a startup, so it is better to do equity funding).
(3) Working capital (current assets - current liabilities): some companies have positive (they receive the revenue cash before dispensing the costs cash) working capital, using their customers' money to expand the operations, others have negative working capital, requiring external funding to expand their operations.
My guess is that (2) and (3) don't apply for AirBnB, they are not a capital-intensive business, and as they get paid when the booking is done but pay out when the guest arrives, their working capital might actually be positive. So they probably need it to expand operations.
Then you need to publish your results for this year. How do you do it?
P&L statement:
Revenue: $100
Costs: $50
Profit: $50
Cash flow statement:
Cash from sales: $0
Cash paid to suppliers: $50
Net cash flow: -$50
So you had a negative cash flow, but was profitable.
Is airbnb losing money, because it now has 1 billion dollars less in cash, and 1 billion dollars more in gold bars?
No, it is not.
Gold is highly liquid, and from what I've read, it can be considered (in bullion) cash equivalents, except for banks, that due to Base 3 regulations can only consider part of their gold holdings as cash equivalent for liquidity purposes.
http://www.businessinsider.com/airbnb-builds-hotel-japan-com...