> With the growth they had last year and current growth, their revenue should exponentially rise over 2014 and 2015.

You're assuming:

A) Their growth stays the same as it is now.

B) Users on year-long free trials will convert to paying users.

These are crazy assumptions absent years worth of data.

Not saying WhatsApp doesn't have something good going, but in what world have either of the above things ever been predictable in this short of time?

Especially to validate the claim "revenue should exponentially rise"...?