That's not an actual argument though.
It's your gut justification that no one should be able to set the amount posed as a question. You are presuming that just because there's no perfect agreement on an arbitrary number, then the problem somehow becomes not worth solving.
> If the global GDP per person is less than $14k, why set at a billion, why not much less? How about $100k?
Good questions. We can have a discussion about it, but that doesn't mean there's never going to be a number that we can agree upon.