The Gra tried to deal with this problem by putting his signature on the letter of excommunication that warned people about these fake scholars that are actually demons.
The trouble is that until this problem is taken care of there is really almost no way to keep Torah. The entire religious world is a den of the Satan and his minions. So one can try to keep and learn Torah by oneself. In fact nowadays that might be the only way. [Though I think of few places that are still pure, like Ponovitch and the great NY Litvak yeshivas. But these kind of places are rare.]
This problem was noticed by the prophets and brought also in the Gemara. It is mentioned also in the Mishna as far as I recall. The place that I remember most vividly is towards the end of Tracate Shabat. There the sages said, "When you see a generation that troubles are coming upon it, go and check the judges of Israel. For all troubles that come into the world only come because of the judges of Israel, as it says in the verse 'שופטיה בשוחד ישפוטו וגו "Its judges judge with bribes."
So we see this problem has been around ever since the time of the prophets and the Mishna. As long as there have been true prophets, there have also been people that figured out ways of making money and getting power out of Torah.
[Thus, keeping Torah sincerely has always been a personal project. ]