whatsapp's entire business model is charging 1$ per month. for a little less than 19bn $ you could:
- build an app doing exactly the same
- run a media/marketing ad blitz
- charge 50c per year. or make it for free, until whatsapp is dead.
if it's about the awesome talent at whatsapp, 32 engineer can be hired for 19bn $. each one of the whatsapp members could have been acquired for less money besides the 2 founders.
it makes no economic sense. as in old school economics, not the valley funny money one.