Well, luckily the people who died fighting in World War 2 cared about their society’s descendants, otherwise why bother fighting and dying? If your future society doesn’t care about you, why risk anything for them?
Once I am dead though, there is no me here to respect any more. Death is complete separation from this world. The vast majority of people who have ever died are completely lost to memory, whether they wanted that fate or not. And for those we do still remember, they’re long past having the ability to care at all what happens to what they left behind. Whether through nothingness or an afterlife, they are no longer here.
We've evolved to care about our descendants, not our ancestors.
Majority of people dying were civilians.