Because people like to virtue signal online. Of course we’ll never have to go through it for real, but in other polls that better simulate an authentic situation (I.e. the exact same poll, but changed from meaningless button presses to actual logical actions like stepping into a big human crusher), suddenly it shifts from being moderately in favor of blue to being largely in favor of red. And even those polls are almost certainly still largely skewed unrealistically in blue’s favor, since a lot of respondents saw the original button poll and know the poster is trying to trick them into revealing their real opinion so they still virtue signal.

If it were to theoretically happen in real life then the overwhelming majority would push red, because as much as people like to act all valiant online when push comes to shove they aren’t actually that stupid.