Whatsapp makes extremely little revenue right now - like it would take Facebook hundreds of years to recuperate what they paid [1]. Even if it doubles in user-base and grows by an order of magnitude (on top of that) through some magic Facebook monetization strategy, it would still take them decades.

But if we discount the fact that Facebook mostly paid their own "worthless" (mostly overhyped/overvalued) stock for this overvalued Whatsapp acquisition, then maybe with an order of magnitude profit, they could recover the money somewhere between 10-20 years.

For Facebook's sake, they better hope some other new disruptive technology doesn't come along in the next 10-20 years, because they won't be able to keep this sort of acquisition strategy for long.

I've noticed some articles call Facebook/Zuckerberg "smart" for noticing Whatsapp is disrupting them - if you can call noticing a disruption so late in the game that you now have to pay $19 billion to buy it, and with almost zero expectations of recovering the bulk of the money in the next decade.

What would be much smarter is using your own engineers to build that next disruption, or at least buy the ones appearing very early in the game. Zuckerberg could've bought tens of such apps in their early days a few years ago, and he'd still be much better off today. He could've owned Whatsapp, Kik, Viber, Line, and many others for much less.

[1] - Analysis of Whatsapp's revenue and profit when it had half the user-base it has today:

http://www.quora.com/WhatsApp-Messenger/How-much-revenue-is-...