Trump has spent much of that time attacking the father and mother of a Muslim U.S. serviceman killed in Iraq. He has made a point of refusing to support Paul Ryan or John McCain in their upcoming primaries. He accepted someone else's purple heart and said that his business investments amounted to "sacrifices."
Even if you think Trump's remarks were defensible, you should be able to see how a hostile press would feature them in the most damaging way. Mainstream media inevitably slants things against Republicans. You may not like it, but if you're a rational adult you take it into account.
The opportunity cost for Trump and for his party is that he failed to direct attention to what he could have made Hillary Clinton's glaring weaknesses.
One was highlighted by the GDP figures announced Friday, showing just 1.2 percent economic growth in the last quarter. Clinton, as the candidate of the incumbent party, had to promise to continue and extend its macroeconomic policies. The GDP figures make a powerful case against that.
Another was Clinton's performance on the Sunday talk shows. FBI Director James Comey "said that my answers were truthful," Clinton said. Of course, Comey said the opposite -- repeated Clinton statements about her emails were just not true. Washington Post fact-checker Glenn Kessler gave her a maximum four Pinocchios for her statement to the contrary.
She also said that the multiple family members of those slain in Benghazi who said, back then and now, that she attributed the attacks to protests at a video must have been mistaken about what they heard.
Trump thus had plenty of fresh raw material to fill multiple campaign days discussing the mendaciousness of "Crooked Hillary." He might even have raised the more unnerving possibility that, surrounded as she typically has been by sycophantic aides, she actually came to believe what she said. No one wants a president who is delusional.
The third opportunity cost for the Trump campaign is time missed attacking Clinton for the most leftward party platform and agenda ever, as Ross Douthat argued in his New York Times column.
For nearly 40 years, abortion has been allowed but not subsidized by taxpayers. Clinton now wants taxpayer funding. Large majorities of Americans disagree.
Voters don't want to see all 11 million immigrants here illegally deported immediately. But they also don't want Clinton's policy of deporting no one but convicted felons -- an open border policy that incentivizes illegal immigration for decades to come.
Clinton also promises to crack down on fracking, which has vastly reduced gas and utility prices, and to put restrictions on gig economy services like Uber. Not much to like here for drivers and millennials.
Plus, she wants to amend the First Amendment to allow government to restrict and prohibit political speech and, in a breathtaking non sequitur, argues that this will stimulate economic growth. She may feel the need to argue that, inasmuch as almost none of her other policies would.
In other words, the nominee of the challenger has a target-rich environment here. But instead he launches a Hatfield vs. McCoy-type feud against two Gold Star parents.
So Trump is strengthening rather than weakening Democrats' argument that he is too erratic, impulsive and ignorant (doesn't he know Russia annexed Crimea?) to be president.
Hillary Clinton's strategy is to disqualify Trump and to attract high-education Republican voters to support her, as Lyndon Johnson did in 1964. She may remember this from the days she was a teenage Goldwater girl. She's hoping that, as in 1964, they don't notice she's supporting an expansion of government that promises to be both dysfunctional and unaffordable.
But remember that Johnson used his victory to bring in the Great Society. Clinton, if she is sincere about her platform, would probably try to do the same.
Now many will scoff at the idea she's sincere. She's a congenital liar, as William Safire wrote 20 years ago, and she showed that again in her mendacious -- or delusional -- replies to questions about her emails.
That said, let's consider the possibility that Clinton is sincere. Many have explained her journey from the triangulation of the 1993-2001 Clinton term as a necessary tactical concession to Bernie Sanders. But did she have to go as far as she did?
The Bill Clinton of the 1990s would not have so advised. He would not have advised bringing the mother of the felon Michael Brown to the public spotlights at the Democratic convention.
Yet, Bill Clinton doesn't seem to have set the course of this campaign. One worry, you would think, about a Hillary Clinton campaign is that she would seem to be a candidate to be manipulated by her husband. But neither her managers nor her opponents nor the public seems to give this much credibility.
One reason may be that she has made such a policy journey. Another is that Bill Clinton has, mostly, not chimed in on policy issues, or even on politics. A third may be that he's not at all in charge, and content to let Hillary take the lead, almost as much as the elder George Bush was content to take his son take the lead in his candidacy.
There's much in her platform that leaves her politically vulnerable. It's popular with a shrunken Democratic primary electorate, but not so much with the general public.
Maybe she is counting on voters to think that she, unlike Lyndon Johnson, won't be able to turn the bad parts into law. There's a lot of reason to assume Republicans will hold onto their House majority, and they have a good chance to hold onto their majority in the Senate.
But there's also the possibility that Hillary, liberated from Bill's strategizing and liberated by Trump's unacceptability to many voters, really believes she can get a lot of this done and set a course for the Democrats in the future. It seems unlikely, but maybe it's possible that the Hillary you can see (although lots of voters aren't paying much attention) is the Hillary you will get, if she is elected.
The media now are buzzing with speculation that that Trump backers like Newt Gingrich and Rudy Giuliani are plotting an intervention and that Trump might drop out or be forced out of the race. That's not likely. He knows he won't increase his chances of winning by withdrawing. But does he understand that he'd increase them by concentrating on attacks on a vulnerable opponent?
Even free-market economists admit there are market failures in the real world. In the political marketplace this year, we're seeing market failures galore. A weak Democrat pre-empted her party's nomination and the incentives in a multicandidate field prevented opponents from deconstructing a weak front-runner.
Yet, Trump's eccentricities threaten to elect as president a congenital liar who is way to the left of the public. That's a big opportunity cost.