They're looked down upon naturally. Evolution ensures that the "goal" (and I use that word loosely, but you get what I mean) of a species is to replicate, and in order to replicate, one must survive, thus survival is generally thought of as one's primary ambition. Consciously deciding not to ensure your own survival is aberrant behavior.
Consciously deciding not to ensure your own survival is aberrant behavior.
So everyone who chooses a job they need to drive to instead of a local lower-paying job is aberrant? Everyone who chooses a car for looks instead of safety rating? Everyone who goes out without a first aid kit? Everyone who eats barbecued food known to be higher in carcinogens? Everyone who works with power tools? Everyone who walks by a main road when there's a 10-mile longer route away from traffic instead?
(These are the sorts of decisions along the intensity of wearing or not wearing a bike helmet).
Guy-risks-self-saves-life-becomes-hero-wins-girl is a very common story line. Guy-is-coward-wins-girl less so.
Those activities aren't perceived as risky. They are to some extent, though probably not as much as riding a bike on high-traffic roads (with or without a helmet). Most people drive their car every day and will never get in a serious accident. Every frequent bike rider will hit their head on pavement a few times.
But again, it's all perception. Driving without a seat belt is considered similarly stupid. The reason is that the cost of wearing a seat belt (like the cost of wearing a helmet) is trivial and the benefits are (or at least would seem to be) significant.
The last thing you mentioned is something entirely different, called altruism. That's shown in many animals, and is a case of choosing replication of a gene over survival. It's entirely unrelated, and it also occurs a hell of a lot more in movies than it does in real life.
