They didn't.
Without American support going to the western front, the Nazis would've been able to dedicate more resources to the eastern front, it would've been an even worse bloodbath ending with the destruction of the Soviet government.
And that's before you factor in the American weapons, materials, and vehicles that carried no small part of the Soviet war effort.
So in theory, and don't hate me for saying this, dont think too hard about it, but was it sorta...a...good thing they bombed pearl harbor?...Don't kill me, its an honest question.
Without American support going to the western front, the Nazis would've been able to dedicate more resources to the eastern front, it would've been an even worse bloodbath ending with the destruction of the Soviet government.
And that's before you factor in the American weapons, materials, and vehicles that carried no small part of the Soviet war effort.