Trump tapped into people's anger at the politicians and political system they (the electorate) unknowingly created. As with many cases where people don't understand root causes and make even bigger mistakes trying to fix them, a portion of the electorate rallied around a guy who tells it like they think it is. Well, more precisely, he presents words in a manner that people mistake for 'telling it as it is', while contradicting himself, exaggerating, or just flat out making stuff up the same as most other politicians. But just like a dog who responds to tone of voice instead of the words, these people do mental gymnastics to convince themselves Trump's not a terrible candidate.
A guy commits to an obviously false mischaracterization of a neighboring country with close ties to us, is called out on it, and responds by imagining his make-believe wall a little higher....that's what it takes to impress you? If someone tells you they have a unicorn in their backyard, are you similarly impressed when they later tell you it's a slightly bigger unicorn?