@engine
More users and that figure drops per user.
More interesting questions are:
What is the life span of a user?
What is the cost to acquire a new users?
How do they expect to earn revenue from each users?
Assume that they are able to fully monetize the user base today (not actually the case). Assume an ROI of 25%. That would mean that they expect to earn $600 of revenue per user per year. Maybe I am looking at this wrong but that seems extreme. At a 1$ per ad click, ( I wish I had an average CPC of a 1$), that would amount to on average about two ad clicks per user per day every day forever.
Note about ROI, 25% seems low given the extreme risk of such an investment.
The great part about the company now being public is that all the above questions can be answered and are of public record.