I agree the US shouldn't have gone to war in Europe in 1917, Iraq in 2003 and Libya in 2011. And I agree Roosevelt was a liar and a pawn of the Chosen Ones.
But in WW II the US had no choice after being attacked at Pearl Harbour in December 1941. To honor his treaty with Japan, Hitler declared war on the USA. This was a bad mistake - after all, in June 1941, the Japanese hadn't honored their agreement with Germany and declared war on the USSR.
Although he had some highly intelligent men around him, Hitler himself made some stupid, impulsive decisions. In 1939, Goring, who was a good man and innocent of the charges brought against him at Nuremberg, advised Hitler to not send troops into Poland because it would cause a war with France and Britain. But Adolf chose to not listen, and the rest is history.