See, here's the thing about Trump....
I mean, this is a dude totally lacking in qualifications for public office. He has no expertise in any area which would lead us to believe he'd make a good president (despite the facility with which he says that others don't know what they're doing!). He's unacquainted with the most basic information he'd need to deal with the problems he'd face. He's apparently congenitally unable to admit to being wrong (how, then, could he learn from his mistakes in office?), and is lacking in even the most basic diplomatic skills.
What recommends him for the presidency, then? Why are so many people attracted to him as a candidate?
Answer: He has bad manners, gives public vent to their own frustrations, and refuses to apologize.
ADDENDUM: Here's more on the wholly irrational- and disastrously misguided-tanTrump on the part of angry Republican voters.