I think it would be fairer to say that Hitler was a product of his time and place, albeit more influential than most. The declaration of war on the U.S. was apparently greeted fairly well in most parts of Nazi Germany (and in most parts of the UK, too - so a perfect crowd-pleasing solution!).
The bigger point though is that the Nazis recognized correctly that they could not just grow to become a leading world power without stepping on the toes of the other world powers. Therefore, war with the other powers is a question of when, not if. They're going to declare war on you eventually, if you don't declare war on them first. Therefore, you may as well choose a time that seems to be to your advantage. Declaring war on the U.S. when he did gave him credit with the Japanese and justified U-boat attacks on American shipping.
In hindsight it was obviously a bit of a blunder, but Hitler didn't have a very good understanding of how democratic politics worked in Britain, let alone in the United States, so he had a hard time understanding how an action like a declaration of war would influence U.S. political decisions. Particularly after he'd already underestimated French and British willingness to go to war over Poland, I think Hitler really did not understand how much his actions would be a thumb on the scales in Washington.
To the extent he did, though, it's still not a completely insane idea. He didn't think he could actually invade the U.S. in 1941, but if he could defeat any attempt to invade Europe, that would be just as good. And he might have been able to, if not for the catastrophe in Russia, but that is another story.