Read a bit more about it. From another article: Beasley acknowledged that “$6 billion will not solve world hunger,” adding that that “it WILL prevent geopolitical instability [and] mass migration.”

Also, there are many cases of WFP's donation causing more problems, like bankrupting local farmers (when giving food), or increase political corruption (when giving money).

So, it seems it isn't as simple as just donating $6 Billion would have ended world hunger, but it would have mitigated a specific, current issue.

Thanks for the explanation!