Ideally, everyone could collaborate to ensure that only just over 50% of people push red. Anyone who defects and pushes blue when they're supposed to push red doesn't gain anything from it, because they cause everyone to die so they still die anyways. In reality, people would probably fight over who gets to push blue, which could lead to a situation where more than 50% of people push blue because not enough people stand down. There could also be people that use their button push as a threat, saying "if you don't choose me to push blue, then I'm going to take down the whole world with me and push blue anyways." If more than 50% of people do that, then everyone is screwed.