no. it's a company. It's valued on future potential. Same as Whatsapp can be valued at $19billion, despite only having $10 million in revenue. Many examples; there is future monetization potential, that they're already discussing.
This would probably have been true in 1914. In 2014 it seems like a semantic quibble.
It's not true for everyone, but the fact remains that you can monetise people without them paying you a dime directly.