Push your logic a little farther. Any sane parent would think twice about risking their life for their child's life. Now push another direction... if you'd sacrifice your own life for your child, what about for someone else's child? A few years ago, I ran into the street in front of a moving car to try to save a child I didn't even know. I wouldn't have made it on time; luckily the car saw the child and slammed the brakes in time. But it's interesting to find just how deep one's own altruism will go. (Also interestingly, I did this in front of my spouse and our own children)
There's nothing unusual for being willing to die for a THING. Hell, people have sacrificed themselves in the millions for mere ideas. People fight to the death over tiny scraps of symbolic land.
It may seem stupid to you. It's stupid to me, too. But that's what people do. That's what people are.
millions also voted for trump, Hitler or believe earth it's flat, just because many people do stupid things doesn't make it good/rational, most of the society it's stupid/irrational, that's just fact (sadly democracy with equal voting rights it's best we came with), just because they are in majority doesn't make their acts right unless you identify with them, then good for you and feel free to ignore facts
as for saving someone's else child I would most likely not do it if I would calculate it's too risky for me (unless I would be stupid by instinct), if their own parent/guardian font care about their lives why should I? I don't expect other people saving my children. though it's not fair comparison,I am sure you have minute to decide if you save some piece of art work compared to split second decision to save living being
I also worked in past in insurance companies, after dealing with thousands of accidents my advice it's always run over animal, don't try to save it by avoiding it (unless it's boar or something similar comparable to concrete block/tree), try to fight your instinct, saw way too many dead people or in serious injury because they tried to save some stupid dog/fox etc and then crashed into some tree/building etc
There's nothing unusual for being willing to die for a THING. Hell, people have sacrificed themselves in the millions for mere ideas. People fight to the death over tiny scraps of symbolic land.
It may seem stupid to you. It's stupid to me, too. But that's what people do. That's what people are.