WRX series is a lucky star saving Subaru from losing money. To a car maker as small as Subaru, during the most difficult years since WWII, remaining profitable is simply a miracle. In fact, the much beloved WRX series is not likely to earn money in meaningful amount because of its small scale of production.
Its outdated, ordinary Impreza sedan version also couldnt attract customers. However, WRXs drivers car image impresses people as much as BMWs M badge and Audis Quattro name plate. As an image car, it boosts the sales of those mass production, real money-making models like Legacy and Forester.