Even Krsna, whom we accept as the Supreme Lord, had to go to gurukula and serve the spiritual master as a menial servant.
So all of the students at the gurukula learn how to be very submissive and how to live only for the benefit of the guru. They are trained from the very beginning to be first-class submissive students. Then the guru, out of affection and with an open heart, teaches the boys all he knows. There is no question of money. It is all done on the basis of love and education.
Srila Prabhupada, as quoted in Journey of Self-discovery 1.3: The Science of