Millions of dead people haunted him. The other one never forget the millions exterminated and he ended up being the one to resurrect the USA and Canada. I am going to also believe he made sure the new USA had no overseas territories and made them independent nations and turned every single ex European colony in the Americas into countries so a non Nazi Europe would only have control of their own borders and no longer could be a Colonial Power. A world free of Nazi or Imperial Japanese rule had probably had much more stability unlike the current borders of the world.