What's that got to do with DISASTER dynamics?
Walmart either donated or trucked thousands of gallons of bottled water to Katrina victims. It was part of business-and-community efforts to help people stay alive during a crisis. It had positive PR affects, and was tax deductible 'charity', but it wasn't just to make money.
In fact, they'd have been roundly criticized as exploitative and greedy SOBs if they'd doubled prices on that water, just to make corporate profits, when babies and elderly were dropping like flies from dehydration.