Hitler took a big gamble and failed, he was hoping to beat Russia and reach the Urals for a massive conquest that would make Germany great and invincible but instead the Russians conquered part of Germany. In the eastern war they beat them almost entirely with their own power and my impression is they would still have eventually defeated them and captured the whole of Germany even if America hadn't entered the war. The despised slavic undermen proved superior to Hitler's master race who after Kursk (August 1943) were doomed in the East.