Why did Gertrude Stein declare of the World War 1 survivors You are all a lost generation?

You have to remember this was long ago.

This was the war that Killed a huge percentage of the Men who Fought, those who survived suffered horrible wounds. Those who did not get wounded were mentally scared ad had trouble the rest of thier lives. WHat we call Post Traumatic Stress Disorder now.

WHat it comes down to is It was the lost generaton because the Men that went to fight did not come back "Whole"