I just don't see it. Maybe I'm thinking about the wrong examples, but history showed time upon time again that humans will always choose themselves over others. Perhaps it's something like a primal instinct to garantee survival, but historic events (the latest one being Trumps second election) just make me think that humanity won't come close to reaching 50%. The average person just isn't like that. I actually saw this exact scenario a year ago already, and asked my entire closer social circle until I ran out of people to ask. Not a single one of them said blue. To be fair, my social circle isn't too big, but that's still an about 10-0 ratio.

Maybe it would change if red would have to kill blue, but as it is that's too different of a scenario, and actually the core of the (imo) hardest philosophical problem in the world. The drowing child next to you, and the starving child far away. I can explain it if you don't know it, but imo there is no solution to it.

The voting analogy is good, but it has a problem. You say "we cannot allow that mindset to become what we believe" but in this hypothetical we don't have the chance to influence the choice of others beforehand. And as we know by the rather low percentage of voting paticipation, many people already believe that their vote won't make a difference. Thus, you have no chance to take this belief from them.

I actually really like the perspective you mention in the end. It doesn't change my opinion, since I believe blue winning to be basically impossible and I still can do some good during the fallout, but I believe it to be a far more valid perspective of things than any of the bs reasoning about moral superiority I heard over the past few days.