I could see myself being pressured into feeling bad about not sacrificing myself (societal pressures/norms and all of that), but it really doesn't make sense to me to feel bad, and I sort of hope that I wouldn't. After all, why should I effectively doom myself to save them? Why should I feel bad? Why should I trade my life for theirs?

The answer to these questions seems obvious to many people, but I don't get it. Why is this virtuous? Why is this sensible? Why is this rational?