USA won't injure or kill 1 in 25 of young adults in the Iran war, unless somehow Iran does have a nuke and wants to use it, come on.
Quite possibly would end up killing or injuring that many Iranians, though.
Gaza is up to 10% of the population killed or injured in the Oct 7 reprisals: https://costsofwar.watson.brown.edu/paper/HumanTollGaza
Raw manpower is hardly the only aspect of war.
Especially in modern war.
Running out of fancy equipment, for example, causes quite a few problems if your opponent hasn't. Like interceptor missiles.