The linked May 2016 article by David Dunning indicates that Trumps popularity can be explained by the Dunning-Kruger Effect:http://www.politico.com/magazine/story/2016/05/donald-trump-supporters-dunning-kruger-effect-213904
Extract: "The Psychological Quirk That Explains Why You Love Donald Trump
The popularity of the GOP front-runner can be explained by the Dunning-Kruger Effect.
This syndrome may well be the key to the Trump voter—and perhaps even to the man himself. Trump has served up numerous illustrative examples of the effect as he continues his confident audition to be leader of the free world even as he seems to lack crucial information about the job. In a December debate he appeared ignorant of what the nuclear triad is. Elsewhere, he has mused that Japan and South Korea should develop their own nuclear weapons—casually reversing decades of U.S. foreign policy.
Many commentators have pointed to these confident missteps as products of Trump’s alleged narcissism and egotism. My take would be that it's the other way around. Not seeing the mistakes for what they are allows any potential narcissism and egotism to expand unchecked.
But the key lesson of the Dunning-Kruger framework is that it applies to all of us, sooner or later. Each of us at some point reaches the limits of our expertise and knowledge. Those limits make our misjudgments that lie beyond those boundaries undetectable to us.
As such, if we find ourselves worried about the apparent gullibility of the Trump voter, which may be flamboyant and obvious, we should surely worry about our own naive political opinions that are likely to be more nuanced, subtle, and invisible—but perhaps no less consequential. We all run the risk of being too ill-informed to notice when our own favored candidates or national leaders make catastrophic misjudgments.
To be sure, I don’t wish to leave the reader with a fatal hesitation about supporting any candidate. All I am saying is trust, but verify.
Thomas Jefferson once observed that “if a nation expects to be ignorant and free in a state of civilization, it expects what never was and never will be." The Trump phenomenon makes visible something that has been true for quite some time now. As a citizenry, we can be massively ill-informed. Yet, our society remains relatively free."
Extract: "The Dunning–Kruger effect is a cognitive bias in which low-ability individuals suffer from illusory superiority, mistakenly assessing their ability as much higher than it really is. Dunning and Kruger attributed this bias to a metacognitive inability of those of low ability to recognize their ineptitude and evaluate their ability accurately. Their research also suggests corollaries: high-ability individuals may underestimate their relative competence and may erroneously assume that tasks which are easy for them are also easy for others.
Dunning and Kruger have postulated that the effect is the result of internal illusion in those of low ability, and external misperception in those of high ability: "The miscalibration of the incompetent stems from an error about the self, whereas the miscalibration of the highly competent stems from an error about others.""