It seems likely this was a mistake, and not the result of dishonesty or malicious intent. That said, such an enormous mistake should have never been made in the first place, especially by a company such as Facebook.
(And yes, the Wahanegi was much more interesting, which I guess was why the number stuck in my head)
It also earns a tonne of revenue through fraudulent clicks many by competitors. It's a big deal and Facebook needs to make attempts to fix it but the problem will never be completely solvable.