The problem with teachers of religion especially in the Jewish world is actually seen from ancient times. That is the false prophets that were documented in the books of Ezekiel and Jeremiah. And you see this in the Mishna and Gemara. The Mishna brings that the prushim [Pharisees] were מכלי עולם (destroyers of the world). [The group of "prushim" ([Pharisees]) are often confused with the sages of the Mishna,- but these are not the same group. The prushim were the religious fanatics. That would be the religious today. This is the opposite of the sages of Mishna who were not trying to make a show of how religious they were, nor trying to use the appearance of Torah to get others to give them money.

[So even though Rav Nahman of Breslov brings up the problem of Torah scholars that are demons in the LeM Vol I ch 12, he is not the first one to notice this problem]