The majority of Trump's vocal support, the majority of those at his rallies, I'd agree. There's plenty of otherwise intelligent Republicans who support him and intend on voting for him who aren't appearing on camera making fools of themselves.
I was over there earlier this year and one colleague, who has seen almost as much of the world as I have went to great lengths to explain how he felt everything in life should be earned, that there should be no free education, medicare, welfare etc and that the Democrats were ruining the US by giving it all away and encouraging immigration. Another who I later toured the UK and Europe with for a week visiting projects was even more convinced that Trump was the only answer and that another Clinton would be ruinous. When challenged on the loopier Trump stuff both dismissed it as rabble rousing (something his idiotic vocal support prove) and believe that he is using the furore for free publicity but will drop the outlandish shit once in office and run the US like a business again.
I don't agree with them with regards to their politics but they're not the ill educated, passportless goofs we'd like to portray all his support as and I do suspect they may be right that much of Trump's schtick is an act to appeal to the masses and that those same masses will be the most disappointed and hardest hit under a Trump presidency in much the same way many of the most vocal Brexit supporters will suffer most when the realities are felt.
I just hope to feck there's not as many silent, intelligent Republicans out there who still believe Trump is the only option who will bolster the ranks of the idiots in the voting and give him a win despite what all the polls say.