Finally, it's simple: Hitler understood how he (and other German soldiers)
had suffered and died during the First World War. Two-million dead, millions more wounded. It was awful, painful, nearly unbearable.

But he refused to abandon the German leadership, and to place blame upon the nation. "AFTER ALL, WERE THEY NOT DYING FOR GERMANY."

It's all on THE COUNTRY. If a man "dies for his country," how can dying be bad?
Luther Ingram: "If Loving you is wrong, I don't want to be right").

But Hitler, deep down, knew that the First World War was awful. He witnessed and experienced the pain, suffering and death. He wanted to make a statement about this, however obliquely:  to tell the world about the horror he and his comrades had experienced. 

He created the Holocaust to subject Jews to the same suffering and dying and pain
that German soldiers had been subject to in the First World War: to replicate the suffering and dying of the German soldiers; convey the horror.

The Jew in the gas chambers was death at the hands of the nation-state, with glory
and heroism substracted. Hitler was conveying the inglorious nature of death at the hands of the nation-state.