Assuming no possible coordination:
If everybody was rational, we would all individually pick red & be safe without needing coordination, trusting that the sum of individual interests would lead to the most optimized outcome.
Except that many humans are irrational & dogmatic, and driven by idealistic / empathetic concerns, would pick blue, even if that requires coordination which is not guaranteed & which puts them as risk.
Knowing this, even if you’re initially inclined to vote red, the actual moral choice, to avoid the death of those willingly putting their lives at risk, is to vote blue to maximize the chances of saving everybody.
In short, if you know that others are not perfectly rational agents, to save them you have to go along with their irrationality, which is counter intuitive.
Everyone in the world has to take a private vote by pressing a red or blue button. If more than 50% of people press the blue button, everyone survives. If less than 50% of people press the blue button, only people who pressed the red button survive. Which button would you press?