Proverbs 21:20 "There is treasure to be desired and oil in the dwelling of the wise: but a foolish man spendeth it up."
Oil - one of the staples in ancient times.
Wise person keeps a stock of necessary food on hand in his dwelling at all times so that he has a supply for emergencies.
Foolish person spends all that he has until he runs short even of daily food.
In severe depression, many would starve in the midst of a plentiful garden because ignorant of how to store and can home-grown produce.