Egregoros

It's not so much about selfishness as much as it is about literacy. The objectively correct choice is to press red. With how this question is presented, there is absolutely no reason to press blue, other than thinking "well some people might press blue without reading the question so we should all press blue just in case". Putting yourself in what could potentially be a life threatening scenario to save a theoretical person who may or may not exist isn't healthy. I've seen a variant of this question that is, imo, much better - it labels the switches "good" and "evil" instead of "blue" and "red". It's a lot easier to rationalize that a lot of people will feel pressured to press the "good" button purely because it's labeled good imo, and helps show how much the way something is presented alters our actions based on our internalized biases. Simply presenting something as "the good choice" will push people to pick it without thinking beyond that. Like in a video game where you get good boy points for doing something morally awful just because the game's devs thought it was a good thing, so everyone just does the good boy points option and then complains online that they feel bad about being forced to do bad things to get the biggest good boy point number possible.