This is perhaps the best explanation I've seen for Trump's popularity - Marshall Kamena is a registered Democrat and was elected mayor of Livermore, CA. He ran on the democratic ticket as he knew a Bay Area city would never vote for a Republican. He is as conservative as they come. He wrote the following:
Trumps 'lack of decorum, dignity, and statesmanship' By Marshall Kamena, Mayor of Livermore, CA.
My Leftist friends (as well as many ardent "Never Trumpers") constantly ask me if I'm not bothered by Donald Trump's lack of decorum. They ask if I don't think his tweets are beneath the dignity of the office.