It is because a person is himself the instrument of his action that he is praised when or he acquires success, so the doer is censured when he is unsuccessful; nothing else exists.
कर्तृत्वादेव पुरुषः कर्मसिद्धौ प्रशस्यते। असिद्धौ निन्द्यते चापि कर्मनाशात् कथं त्विह॥