I don't think negative infinity is a reasonable number for this. If it were, then I would expect you to gladly pay someone all your income for the next 20 years to stand guard over your children night and day to ensure that none of them are kidnapped and killed. Anything less would be negligent parenting.
I don't think you are taking the word "infinity" seriously. If parents believed that, why are they recklessly endangering their children's lives by taking them to a public place where they could be shot and killed, instead of hiring a personal shopper? Why did they put them in a car when auto accidents are the number one cause if child deaths? Why are they living in America when child mortality is lower in several other countries?
The answer, of course, is that while losing a child is unspeakably awful, children are not infinitely valuable to us - at least if you go by what we do rather than what we say. And public policy needs to reflect that.
