There is a substantial fraction of the US public that does not understand the world. Business is a mystery; government is a mystery; international affairs are a mystery. These are the same people who, if you presented them with a "proposed" set of laws consisting of the Bill of Rights, they would not recognize them as the first ten amendments to the Constitution, and they would oppose and reject them. These are people who think that all politicians are corrupt, and that it takes no skill to be US president. All decisions in their lives are made by gut feelings, without weighing evidence or evaluating the truth of that evidence. They love bombast and arrogance, and can't tell whether someone is truly successful in life or just lucked out. Their favorite sport is professional wrestling, which they don't recognize as phony.
When Mitt Romney points out that Trump is not a successful businessman, but that he inherited most of this wealth and grew it more slowly than a typical mutual fund — they pay no attention. They are interested in feelings, not facts. (I discuss this more in my post Why Study Shakespeare and Geometry.) Trump feels successful.
I know many such people exist, and I believe they are the base support of Donald Trump. I know there are also a few smart and knowledgeable people who support Trump (Ann Coulter, Chris Christie) and I don't understand them; maybe they are playing a higher level of politics than I understand. But I don't think such people are his base.
The big question is this: are such people found only in the Republican Party? If so, then if Trump is nominated, Hillary Clinton will be our next president. Republicans make up only 25% of the electorate; Democrats 31%, and independents 42%. If Trump has 40% support from Republicans, that amounts to 10% of the electorate. He could lose in the biggest landslide ever. (And then for future elections, the Republicans will adopt the Democrat trick of having lots of "Super Delegates" to avoid a Trump-like recurrance.) But are there also such people among the Independents and Democrats? If so, then Trump could really be elected.
And, when the professional wrestler Donald Trump is impeached and removed from office, his VP Chris Christie will become president.