Saying that a product used by 500 Million people (that's ~7% of the population of planet Earth) earned its value by "simply existing" is a pretty hand-wavy.

That's incredibly difficult to do.

I didnt really say that. I said that if it puts Facebook's value at risk, what exactly was that value? Why is it zero sum?

I think that so far it suggests that that hypothetical $50B was worth $31B + whatever positive value WhatsApp has.

This. Facebook did really throw startup valuation out of whack starting with the Instagram acquisition and following up to Whatsapp. They appear to have no idea what they're doing with their money, they're in a rather vulnerable spot with their core business, and their demented frenzied spending seems to have infected everyone around them.

Instagram has turned out to be an amazing acquisition for Facebook. Facebook make >$12 billion dollars in 2014. You're saying Instagram wasn't worth 1 months revenue for Facebook? It's a double digit percentage of all time people spend interacting with Facebook's app constellation.