Strangely enough, Trump supporters interpret Trump's endless falsehoods as evidence of a form of honesty. Trump supporters say, in effect, "he's telling us what he thinks instead of what he's 'supposed' to say." The fact that what Trump thinks is demonstrably false is secondary in their minds.
Another part of it is that many Trump supporters are not looking for someone to peaceably govern the nation, they're looking for someone to smash the government, because they take for granted all the advantages of a civil society and don't realize how rare they are. And if you want a loose cannon, Trump fills the role better than Hillary.