It's well-known to psychologists, public speakers, politicians and con-men that in general the more confident an individual appears, the more persuasive they are to other people. This effect holds regardless of the veracity or provability of their assertions. In other words, confidently and assertively talking horseshit will make you more persuasive than simply talking horseshit on its own, regardless of the fact it's horseshit.
In other news, the Dunning-Kruger effect demonstrates that - in general - the more incompetent or ignorant someone is of a subject, the more they will over-estimate their own expertise or understanding of it. Equally, the more experienced and competent a person becomes in a subject, the more they will begin to underestimate their true level of knowledge or expertise, downplaying their understanding and qualifying their statements. In effect, when trying to assess one's own level of ability in a subject increased expertise is inversely proportional to confidence in your expertise.
The net effect of this is that - again, in general - ignorant or incompetent people are subconsciously predisposed to be more confident in their opinions, and all people are subconsciously predisposed to find confident people persuasive.
In a nutshell, all things being equal, people are instinctively predisposed to find ignorant or incompetent people disproportionately persuasive and trustworthy compared to more competent, more experienced experts.
Distressingly it appears that in the kingdom of the blind the one-eyed man is not king. Instead, in the kingdom of the blind the true king is the one blind guy who's sufficiently incompetent or delusional that he honestly believes he can still see.
This has been your mildly disconcerting thought for the day.
 The author acknowledges that there may be some overlap in these categories.