Basically if you press the red button you are guaranteed survival and if you press the blue button your survival is not guaranteed, but if more than half the population presses it then no one dies.
Would you risk your life to save the idiots who press the blue button?
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?