English is confusing, isn't it?!

In the demographers example, "would" is used to express a conditional. You could almost restate it (roughly) as, "If the demographers are going to develop more accurate forecasts, then they must learn more..." The word "would" is a helping verb; the technical term for it is a modal auxiliary.

We actually wrote an entire post about "would" over two years ago:
https://essaysnark.blocked/2009/09/ ... would.html

In that post, we called it a "hypothetical" - similar to what we've called it here as a "conditional." (These are not necessarily the official grammar rules, these are how EssaySnark thinks about it.)

In the demographers sentence, the key point is that they currently do not konw enough. Because of this current state (lack of knowledge), it would be incorrect to use "will" in this sentence, since "will" is an absolute word. "Will" represents commitment. "Would" leaves wiggle-room. We don't know if they can learn more than they do now; but in order to be successful with more accurate forecasts, that's what they need to do ("would have" to do). Knowing more is a pre-requisite for them making more accurate accurate forecasts; they are unable to do so today.

In the second example you cite, about overcoming a fear, we can't say for certain without the entire passage, however our assumption is that the speaker is making a declaration or vow: This is what I WILL do in order to conquer my fear! He's saying that he's made the decision, and this is what he's going to do!

"Would" just doesn't work there.

Hope this helps!!
EssaySnark