John had to do what he did to Virgin for its survival. Low cost airlines only survive by continued growth in order to take advantages of economies of scale and market share. If you stop growing, your margins are eaten up by cost rises e.g. cogs, fuel, labour etc.
You can't just increase price in this environment. The customer type will transfer to bus, train, or not travel at all. And then you get further hammered by your competitor who has the scale and the capital, to undercut you, and continue to grow. It was a double sword for Virgin. It would be gone today. He did the only thing he could to ensure survival.