1. Any technical evidence to support your statement that sleeper has high operating cost
2. Most importantly there is no alternative to sleeper class no roadways is as frequent, fast and comfortable in comparison sleeper.
3....
more... Railway is for the service of every class of people not for selective privileged people. The basic concept of any government organisation is service for the people and even today when in every train AC coaches are in majority still you are not satisfied. As far as loss is concerned there are many other loss making projects which is nothing compared to revenue from sleeper.