Regarding "huge, across-the-board gains in human flourishing and well-being," how do you envision economics and labor would play out? What does this look like with regard to resource allocation?
Here's a comparison though: War is another of those realities—like aging and death—that we seem to have normalized and accepted at a cultural level. It's fair to ask how economics, labor and allocation would play out once a civilization stops dumping a third of its resources into the destructive act of war, but to ask whether we should end the war, just because we're uncertain of the answers, strikes me as absurd.