NO 19-year old is aware of their own mortality. They don't have the life experience to make an informed decision to put themselves at risk. And recent studies seem to prove the long empirical evidence that teenager-hood lasts until the mid-20s, when the brain is finished developing. It has only in recent years that society has been rich enough, and the lifespan long enough, for the 18-25 year old set to finish growing up physically and neurologically before they started having to make a living and cranking out babies. (Remember, mother nature values reproduction above long lifespan. Crank out the babies, and count on enough village Nanas being around to raise the orphans, but keep the birthrate up.)
Humans are merely gene's way of reproducing.