I believe that Hillary Clinton, who seems on track to have won the popular vote by approximately 2% of the votes cast, lost the election to Donald Trump for three basic reasons:
1. Most fundamentally, there seems to be a very widespread and deep-seated antipathy to Mrs. Clinton.
a) I suspect it traces to her remark, as the First Lady, that she didn’t plan to stay home and bake cookies. I think that remark cut very deeply, insulting not only many women but also the then-prevalent lifestyle of most middle class Americans, or at least the vast majority who live outside of the coasts.
b) Hillary’s persona as a whip smart, active, self-assured and somewhat intellectual woman may have inspired some sexist opposition, especially with her public reserve and instinctive desire for privacy playing into a bad stereotype. But I don’t think that was a primary reason for antagonism to her. After all, there are plenty of such women who have succeeded in politics—Jennifer Granholm, Michigan’s former governor, and Sen. Elizabeth Warren being two obvious examples.
c) The Republican Party, fearing Hillary ever since her attempt to pass a healthcare law in the 1990s, has mounted a decades-long smear campaign against her, using endless Congressional investigations, a consistent policy of lies and distortions, and the rumor-mill of social media. While the attacks largely stopped when she seemed out of politics and just doing a good job as Sec’y of State, in the service of a master slanderer like Trump this campaign built with enormous effectiveness on the old smear campaign.
d) And Hillary made unforced errors, most notably the private email server. By comparison with the misdeeds of Trump and other Republican officeholders her mistakes were trivial, but given the underlying antipathy they could be and were magnified into great wrongs, for many even surpassing Trump’s frauds, lies, tax avoidance, and misogyny. Millions of votes that had gone to Obama failed to materialize for Hillary, due at least substantially in part to these errors and the slander campaign.
2. Hillary ran a campaign that played Trump’s game. This was perhaps the most inexcusable error of all. Trump had demonstrated, with his Republican primary opponents, the folly of getting into a character assassination battle with him. He is a far more skilled slanderer than anyone else on the public stage. Yet Hillary did what the Republican primary losers did. In devoting her campaign to attacking Trump’s character she failed to campaign on her clear advantages in terms of the issues spelled out in the excellent Democratic platform, issues that were designed to appeal to many of the Trump constituents. Had she done so, her Presidency would have been a lot more appealing to a broad swathe of the public. Instead, Hillary’s campaign became a comparison of two disagreeable people, reducing Hillary to Trump’s level and making their faults appear comparable.3. The third reason for Hillary’s loss was FBI Director James Comey’s letter 11 days before the election, resurrecting the email controversy and apparently supporting Republican smears against her. There was no defense against this letter, and no time to overcome its impact. Hillary’s margin of lead ranged from 3-14% just before the letter in 7 national polls, with the average being 6.4%, to 1-3% just before the vote. Since Hillary lost the crucial battleground states by very small margins, it’s clear that Comey’s letter was sufficiently powerful to cause her loss.