OK, kill some cheap easy to replace little airplane thingies with your large, expensive and difficult to replace submarine. Even if you kill dozens of them, the exchange can never be a good "buy." And the little airplane thingies call their buddies, more cheap expendable airplane thingies with bomb thingies aboard to swarm you before they attack and you ever get a chance to shoot them down.
So engaging cheap fly thingies isn't going to get you any medals. It isn't going to help win the war. Nobody will think you are courageous. The admiral will make an example of your sorry carcass and you'll spend the rest of the war peeling spuds....if you survive your foolishness.
