Issar Zalman Meltzer had a disciple that became Breslov.
This was Shmuel Shapiro, the most famous Breslov Chasid of the Pre-World War II generation.
Issar Zalman  said about the person that convinced Shapiro to join Breslov, "I am sure he will never leave hell."
It seems to me that he must have considered the person that seduced him as a "mesis and madiach" [one that tries convince someone else to join a cult of Idolatry.] [See the Nefesh Hachayim concerning the subject of attaching oneself to a Tzadik.

It is hard to disagree with Rav Issar Zalman.

The first thing that happens when one becomes Breslov is the learning of the Talmud stops. Stops cold.
Who can argue with this?  who can deny the basic effect of Chasidut  on people?

hink in connection with a regular Talmud session per day and a regular Musar session per day his teachings are great. But when one goes into this without balance something goes wrong.

There are several levels of insanity. The two most basic ones are simply people that can't function as used to be committed to insane asylums.the other level is spiritual and refers to people like Hitler or a sub-level of that.
What causes insanity.
I hold that a radical change in world view causes insanity.This is when a child is growing up in a loving and caring home and then something happens to shatter his point of view.This causes the wiring in the child;s brain to be severed.At that point it takes super human effort to reset the connections.

Another cause of insanity is to be holding from a world view that has internal contradictions.These contradictions are like a Trojan horse. One is not aware of the conflict on the surface level, but internally these contradictions eat away at ones sanity. This is like how sometimes concrete blocks are made with an steel rod inside  that is purposely bent before the concrete hardens so there will be a constant stress.

Another way is simply by belonging to a group of people that have an insane ideology i.e. one that has internal contradictions and also ignores reality. These last two levels are held by Orthodox Judaism