The fellow had epilepsy. There were a few episodes and then he had a dream of Reb Nachman coming to him telling him if he would come for Rosh Hashanah it would all be OK. He was also saying the entire book of Psalms for 40 days in a row. The event happened on the fortieth day. Apparently it was not as some had thought that he went to the river to dip in "tovel." Rather he went out to do Hitbodadut [Talk with God alone as Reb Nachman emphasized.] He fell in the river while doing Hitbodadut and drowned. No one could find him for a week or two.
This is like the normal question of theodicy. But it is worthwhile knowing that there is a negative side of things when it comes to Breslov. I don't want to minimize it.
But for me Reb Nachman seems basically very good. I can't answer why this does not seem to apply to everyone across the board, even people that are obviously sincere.
One problem I think is that of "Ribui Or" ריבוי אור ("excess light"). But I should mention that questions on Ren Nachman are perennial . And there are new ones all the time. But to me these question just seem like obstacles that are meant to keep me from the good ideas and advice of a tzadik who I feel I in fact get benefit from.
Spiritual things have an aspect of the subject and another of the object. The subject--i.e. the observer supplies the way he sees the reality. So even objective reality will depend on who is the observer. The same reality can turn from good to bad depending on the receiver. סם חיים למימינים וסם מוות למשמאילים בה. That does not mean that that is what happened to that fellow. I imagine he was truly following the advice and path of Reb Nachman to the best of his ability, All I am saying is there are plenty of people that don't and for them it does have a bad effect.
But the bad aspect should not be ignored either. There are pitfalls that need to be avoided. The baali teshuva give great power to their leaders although they are scammers and frauds. There is a tendency to leave one's vocation and or yeshiva and both of these are wrong.