In the case of yamamodo, the japanese government has a lot to lose. And watching this whole thing take place is like watching a guy play a card game where the odds of winning are low and he's bet his family's lives on the outcome. So what does he have to do to win? Well, this offensive attack against the us. Will come out ahead, especially if you demoralize the americans by decimating their fleet at the outset, and get a advantage on them.