You're right. But using fuel hedges to keep the prices low is not really sustainable for a single carrier the size of SWA. They are using their gambling winnings to subsidize customers ticket costs.
Fuel hedging is gambling, pure and simple. SWA has been notoriously successful at it; Parker and the Tempe brain trust has been notoriously terrible at it.
If I owned a good sized company that sold widgets at retail, and subsequently won $250 million playing the PowerBall lottery, I could use those winnings to undercut all my competitors selling their widgets. I could slash my prices to half of my competitors' and thereby have the pricing power to hurt them, possibly mortally. That's what's happening right now in the airline business. SWA has the pricing power because they play a great game of oil-price poker, not because of their admittedly efficient business model.
Good analogy and I agree to a certain extent except that WN had been the most profitabl airline for years...well before they had the fuel hedge advantage. So the fuel hedge gambling is just another tool they hav added to their arsenal.