The difference is that Facebook was within reach of cashflow positive at all times in it's growth, ie if they fired non-core staff could be cash flow positive w

The difference is that Facebook was within reach of cashflow positive at all times in it's growth, ie if they fired non-core staff could be cash flow positive within months (source: Mark Zuckerburg talk I went to). It had ad's from within the first few months of existence, that was Saverin's role before he left/was fired but they always built that part of the business and revenues always scaled with expenses.