This phrase purposefully uses negative adjectives in a positive way. This is what gives this phrase its "punch." Taking a word, phrase, or situation and contrasting how it is normally used versus how it is used in a given case is a common rhetorical device.
Hungry here means "wanting something more", as in "He was hungry for a raise." Jobs is putting forward that being dissatisfied with what you have and wanting more is a good thing.
Likewise, someone who is foolish acts without thinking and takes unnecessary risks. Jobs is saying that you SHOULD take stupid risks and throw caution to the wind.
Taken together, Jobs is simply saying: "You only live once, so make it count and go after what you want no matter what."