Most people would run like hell from the prospect of risking themselves to save others. Most people are terrible. Least, as far as I understand people to be. Sure, they're relatively nice to friends and family, but beyond that, most people are essentially psychopaths. How much is "most" really, I don't know. Half? Nine out of ten? Two or three in ten, but it feels like most because I'm such a bitter old cynic?
It's difficult not to be biased about it. Look at the people we've known, how many of them acted like self-centered pricks, figure that's probably a reasonable cross-section of humanity to call it close enough. Or, you could look at the sorts of things people say on the internet, the people who aren't in your social circles. Would that be more accurate? It certainly skews perspective in the other direction. At best, we take in as much data as we can, and call it from that.
I think most people are terrible. Well, roughly half, with a lot of murky grey area in between. Grey area which I'm still inclined to call terrible. I think it's just how evolution's played out, though. On the most basic level, we're all coded by the simple causality of it, to put our own interest above all others. Doing so is simply, reductively, more Darwinistically effective than not doing so.
At least, until you add another level of complexity, where that straightforward rule gets causally outmaneuvered. Groups of people who are inclined to help the group, even when doing so results in sacrificing themselves, also had the better chance of survival overall. It was their genetic traits which proliferated, often over those groups which were prone to collapse when environmental stressors forced too many selfish decisions. When group dynamics were critical.
Nature works in fuzzy ways though. This isn't a binary distinction. It runs along a continuum, from one end of the spectrum to the other. At different times, and in different places, different proportions of these counterbalancing factors have been more or less effective. We don't know which genes might be responsible, and what the biological mechanism might actually be - but chances are pretty good that it's something that quantifiably varies.
Some people are just going to be more altruistic than others, but there's also going to be a natural tendency towards thinking people at different places on the continuum are fundamental threatening our very existence. The coding that tells us that the other side is wrong is there because it was an effective survival measure. In our genetic experience, their side got everyone killed.
[the random facebook post that came across my feed, which inspired this]