Here’s why:
Reported in The New Yorker on July 16, 2015, a few days after a Trump campaign rally held in Phoenix, in McCain’s home state, McCain offered his displeasure over the rally. “It’s very bad,” he said. Going farther, “[t]his performance with our friend out in Phoenix is very hurtful to me,” McCain said. “Because what he did was he fired up the crazies.”
This rally was held on Saturday, July 11, 2015, as reported by Politico. The dates are important.
Trump-supporters are “crazies,” according to Senator McCain, those people willing to stand in line for hours to see and hear their favored candidate for president. I wonder if McCain ever had such crowds at his campaign rallies in 2000 or 2008, at least before he brought Sarah Palin onto his ticket.
Insulting Trump-supporters is the same as insulting Trump, at least in Trump’s view. As he is hardwired to do, when insulted, he hits back.
In Iowa, a week later, on July 18, 2015, Trump was interviewed and delivered his response to McCain’s calling Trump-supporters, and, by default, Trump himself, “crazy.” Trump said, “He’s not a war hero. He’s a war hero because he was captured. I like people who weren’t captured.”
The feud was off and running, but who started it? From the dates, McCain drew first blood, and Trump responded as he always does: with a right cross.
“I like people who weren’t captured” is where he lost it, he had to add this final, all encompassing BS comment, making sure that every family who lost a loved one as a POW was captured because they were stupid, thus unlikeable. OR a POW who gave years in captivity. It was a senseless comment and achieved nothing..