My dear Vyāsa, even though a devotee of Lord Kṛṣṇa sometimes falls down somehow or other, he certainly does not undergo material existence like others [fruitive workers, etc.] because a person who has once relished the taste of the lotus feet of the Lord can do nothing but remember that ecstasy again and again.
A devotee of the Lord automatically becomes uninterested in the enchantment of material existence because he is rasa-graha, or one who has tasted the sweetness of the lotus feet of Lord Kṛṣṇa. There are certainly many instances where devotees of the Lord have fallen down due to uncongenial association, just like fruitive workers, who are always prone to degradation. But even though he falls down, a devotee is never to be considered the same as a fallen karmī. A karmī suffers the result of his own fruitive reactions, whereas a devotee is reformed by chastisement directed by the Lord Himself. The sufferings of an orphan and the sufferings of a beloved child of a king are not one and the same. An orphan is really poor because he has no one to take care of him, but a beloved son of a rich man, although he appears to be on the same level as the orphan, is always under the vigilance of his capable father. A devotee of the Lord, due to wrong association, sometimes imitates the fruitive workers. The fruitive workers want to lord it over the material world. Similarly, a neophyte devotee foolishly thinks of accumulating some material power in exchange for devotional service. Such foolish devotees are sometimes put into difficulty by the Lord Himself. As a special favor, He may remove all material paraphernalia. By such action, the bewildered devotee is forsaken by all friends and relatives, and so he comes to his senses again by the mercy of the Lord and is set right to execute his devotional service.
In the Bhagavad-gītā it is also said that such fallen devotees are given a chance to take birth in a family of highly qualified brāhmaṇas or in a rich mercantile family. A devotee in such a position is not as fortunate as one who is chastised by the Lord and put into a position seemingly of helplessness. The devotee who becomes helpless by the will of the Lord is more fortunate than those who are born in good families. The fallen devotees born in a good family may forget the lotus feet of the Lord because they are less fortunate, but the devotee who is put into a forlorn condition is more fortunate because he swiftly returns to the lotus feet of the Lord, thinking himself helpless all around.
Pure devotional service is so spiritually relishable that a devotee becomes automatically uninterested in material enjoyment. That is the sign of perfection in progressive devotional service. A pure devotee continuously remembers the lotus feet of Lord Śrī Kṛṣṇa and does not forget Him even for a moment, not even in exchange for all the opulence of the three worlds.
(Śrīmad-Bhāgavatam 1.5.19, Text and Purport)