That's the $64,000 question Curtain Jerker. The Japanese attacked Pearl Harbor because they feared the U.S. would not have remained neutral if they moved south. Would the U.S. have remained neutral if a major source of the resources you mentioned was cut off? Not to mention would they remain neutral if this resource center was cut off from the UK and Free France. I suspect even the America First crowd would be getting uneasy at this point with Japan taking such an aggressive stance.
At least this way Japan might avoid a war war with the US, so it's high risk but better than suicide. And if the US still declares war, at least a compromise peace might be possible as there wouldn't be the wave of fury and patriotism that followed PH.