L. Ron Hubbard was psychiatrically ill, he did evil but it's not clear how far he was responsible for his actions.
Yet, Hubbard was dubbed "schizophrenic and paranoid" by a California Superior Court judge, and Scientology dismissed as "immoral and socially obnoxious" by a High Court judge in London. 
Now, decades after Hubbard's death it may be difficult to determine how far Scientology was Hubbard's psychotic delusion and how far Scientology was deliberate fraud, see List of lies made by L. Ron Hubbard. Either way rational people shouldn't take Scientology seriously.
Quotes from L. Ron Hubbard
For those of you whose Christian toes I may have stepped on, let me take the opportunity to disabuse you of some lovely myths. For instance, the historic Jesus was not nearly the sainted figure has been made out to be. In addition to being a lover of young boys and men, he was given to uncontrollable bursts of temper and hatred that belied the general message of love, understanding and other typical Marcab PR. You have only to look at the history his teachings inspired to see where it all inevitably leads. It is historic fact and yet man still clings to the ideal, so deep and insidious is the biologic implanting. It is a good joke that the Galactic Confederacy is associated with the Serpent in the Garden, the beast and other emissaries of the "Prince of Darkness". Yet in certain passages and esoteric interpretations of the Bible (much of which has been taken out and effectively suppressed for centuries) as well as the Cabbalah, the truth reveals itself quite nicely for the clever and the ungullible.