The Russians started the damn war with the Germans. And they lost so many because of Stalin purging his best Generals before the war, and not being prepared when Hitler invaded.
Actually the Germans invaded the Soviet Union in 1941 as I think you meant to say.
Hitler invading Russia lost him the war and he probably knew it by late 1942.
Reminds me of a quote by Hitler who stated angrily to Guderian at a meeting in Russia in the summer of 1941:
"If I knew the damn tank statistics you quoted in your book [Actung Panzer] were true I never would have started this bloody war" i.e.against Russia.