That the impacts on adults are negligible compared on children is irrelevant, because they are multiplied by 0, since they don't apply to you, so you only consider the infitesimal effect it has on you as an adult.
For any parent with a child, it goes the other way, but with a slightly different mechanic. There is an effect on the adult, but it is so minor compared to the effect on children, that the proportionality causes you to dismiss the minor inconvenience it poses to adults, since you are focusing on the question of what happens to children.
Nothing wrong with being (very) selfish though, just pointing out the dynamic.