Germany did not use conscript armies. What does this mean? They had limited manpower. That means, there is no way in hell they could have conquered the world. They simply didn't have the resources to complete it. They were losing many men on the Russian front. When the Americans joined in, the Germans were already on their way down. They were eventually going to lose, anyway. Their industrial production couldn't compare to the US. We built more guns, ammo, planes, and bombs, faster than they could. In hindsight, they had no chance. The reason they sent U-boats into American waters was to stop our arms shipments because they KNEW they couldn't outproduce the US. Sending our military over there wasn't necessary. They would have collapsed, eventually. Though, ending the war sooner did save many lives.You really should read up on your history friend. France had fallen and Brittan was on the brink. The Nazi's allies Japan attacked us, ever heard about the German U-boats off our west coast? The battles in the South Pacific?
My grandfather fought in WWII - I'm a WWII buff. trust me.
Japan attacked us because we were interfering with their oil production. We even baited them into it, by bringing our entire Pacific fleet to Pearl Harbor (where one of my great uncles died on the Oklahoma). Here's the thing with Japan, though they were allied with Germany, they never wanted to conquer the world. They were trying to secure resources. Yes, they were brutal, but they never were a threat to the US.
Remember, this all started with your statement that if it wasn't for the US, we'd all be speaking German. That is patently false. Even if they conquered the entire planet, we would still be speaking English.