A few decades ago, conservatives opposed zero-sum thinking because they believed (or claimed to believe) a free market would create extra slices of pie to feed everyone.

But now, Trump and the present-day Republicans use zero-sum thinking to (as you point out) instill fear and insecurity in their followers.

Speaking of game theory, you're probably familiar with the dollar bill auction. Today's climate of irrational behavior that promotes what seems like self-preservation but is actually self-destruction reminds me of that exercise.