Why are so many self-anointed "prophets" so wrong?

I have just reached a new mathematical conclusion:

Claimed infallibility × theological accuracy = a constant.

As I write this, I am listening to a program titled "Wilderness Restoration" hosted by a self-styled "prophet" named Walter Becker who claims to have received a prophetic mandate from Jesus Christ himself while in the womb. For the last half-hour, he has been ranting and raving about the "1611 AV Version King James Bible"¹ and saying stuff like this:

• other Bible translations are "New Age Communist Babylonian Communist Bibles of hell" (yes, he actually said that precise sequence of words)
• they were translated by men possessed by the Devil
• the KJV is a "word for word translation" of the Bible given directly by Christ himself
• Jesuits and "Red Communist parasite snakes of hell" have been working since 1611 to pervert the Word of God
• "King Jesus" called King James to correct the "errors" of the Geneva Bible
• the "true" Biblical manuscripts are the ones that came from Antioch because Christians were "first called Christians" there, and the manuscripts originating in Alexandria, Egypt were "butchered up," just like the "Roman Catholic bastard whore church of hell really is"
• reading the "1611 AV Authorized Version King James Bible" is the path to getting right with God
• you aren't really right with God if you don't appreciate the thees and thous, because "you don't like the way King Jesus talks."

(And you thought God And Riplinger and Dr. Petey were wacko.)

But then he went on to make the following theological statement: "Jesus Christ is the Holy Father. Jesus Christ is the Holy Ghost." This is nothing less than the ancient heresy of Sabellianism, also known as Modalism or Patripassianism. These days it is most often manifested in so-called Apostolic² or Oneness Pentecostal churches. Modalism teaches that the Godhead is a radical unity, not a Trinity: that Father, Son, and Holy Spirit are not one God in three persons, but one person with three different roles.

What is it about people whose theology is so off-base, that they have to claim this kind of divine authority for themselves? And why is it when someone does claim to be some kind of prophet, invariably they are going to say something that is transparently ignorant or heretical? I can't theorize on why this is. I can only accept it as a truism. You never see a mature, well read, learned Christian who is orthodox in his theology, claim to be a "prophet" in the Old Testament mode. They know better than to blame God for their idiocy.

Footnotes

¹ Corollary 1: The longer the title that someone uses for the AV, the larger the quantity of KJV-only Kool-aid he has drunk.

² Corollary 2: Churches that call themselves "apostolic" generally aren't.