The US government had very little choice but to get involved in WWII in 1941. After the Japanese attacked Pearl Harbor, public opinion was so inflamed that there was no way to avoid war even if President Roosevelt had wanted to. By declaring war on the US, Germany made that decision easy as well.
That said, was it wise to go to war because of Pearl Harbor? If you want to, you can argue that it was not. Going to war meant the loss of huge amounts of money and, much more importantly, thousands of irreplacable lives just on the American side. All of this to get back the Philippines and Guam (in terms of things that had belonged to the US before the war). If you look at it in that way, you could say that the US should simply have shrugged off the attack. However, it is practically unthinkable that such a decision could ever be made in real life.