The phrase “Stay Hungry, Stay Foolish,” is an aspirational slogan adopted by Apple founder Steve Jobs. It represents a conscious attempt by a successful man to emulate the strategies that he associated with achieving his success.
Mr. Jobs was attempting to express the opinion that the most daring choices are made from necessity. He believed in desperation as a form of manufacturing that necessity, and he demanded of himself that he emulate conditions of necessity in order to produce in himself the motivation that he felt he required to produce at his best level.
The idea is that hungry people will work harder, and that foolish people will attempt things that more reasonable to people or not. It implies that necessity is not only the mother of invention, but that necessity can be simulated in order to spur more invention.
It must be made clear that this is an aspirational slogan, and that the people who adhere to the slogan do not do so literally. It is good to be hungry in the sense that it is easier on your body to have a more sparse diet. It is not good to not be able to get enough food, and the idea that caloric insufficiency increases productivity does not seem supported by the data. By the same token, Mr. Jobs was most certainly not a foolish man. His work habits were more characterized by excessive rationality and cautious elaboration on what came before then anything that could be described as foolish.
Careful examination of the phrase shows that it is essentially an athletic advertising slogan. It is the thing that competitive people say to themselves in order to compete more fully. It contains the obverse of insight, so it has little intrinsic meaning.