A world war? In this day and age, we have made many economies and states mutually dependent on each other and all-out world wars like WW 1 and 2 is unlikely to happen.
You still have madcaps like Trump and Kim Jung with nukes in their arsenal, anything is possible. You cannot expect everybody to act in a rational way. When we do have WWW-III on the cards, people should be stockpiling sacks of grains and food, not trying to protect their wealth. It is during times of distress that we realize the importance of basic needs.