Devotion to a spiritual teacher is not for the sake of the teacher, it is for God.

In the history of the great and holy beings of the world the greatest and the most blessed have been the devotees. ... devotion teaches one virtue; sincerity, earnestness, the sense of duty: all different virtues come by devotion. A person who is devoted to anyone in the world, to one's father or mother or brother or sister or children or friend, has taken the first step in devotion. But the one who shows his devotion in the spiritual path to his teacher he has taken his second step. He has only to take one more step and he will be there. And that will be the devotion to his ideal.