Another answer that seems suspiciously self-serving. There are various moments between them that are already public record thanks to Comey that might more reasonably explain Trump’s hostility to him than what he claims here. There was Comey resisting his repeated pleading to say publicly that the president wasn’t under investigation in Russiagate. There was also the moment a few weeks before Trump was sworn in when Comey pulled him aside at Trump Tower to let him know that the FBI had information that, ah, the president might be into water sports.

Instead Comey thinks he lost Trump by interjecting at a meeting to let him know that the U.S. government is not, in fact, a thugocracy like Putin’s government is. Go figure that our super-patriot former FBI chief supposedly earned Trump’s hate by challenging him about the importance of democratic norms, precisely the thesis of his new book. Here he is talking about a meeting he had with Trump and others after the Super Bowl last year at which Trump brought up an answer he’d given in his pre-game interview with Bill O’Reilly. O’Reilly asked about detente with Russia and noted that Putin’s a killer, to which Trump replied with his stock MAGA response: “But we’re killers, too. You think our country’s so innocent.” He was proud of the supposed cleverness of that, noted Comey:

GEORGE STEPHANOPOULOS: So the president wants you to say this was a good answer.

JAMES COMEY: Yeah. In fact, he was telling me it was a good answer and then said– gave me an opening by saying, “You think it was a great answer. You think it was a good answer.” And then he was starting to move on. And I jumped in and I said, “Mr. President, the first part of the answer was fine, not the second part. We’re not the kind of killers that Putin is.”

And when I said that, the weather changed in the room. And like a shadow crossed his face and his eyes got this strange, kinda hard look. And I thought in that moment, “I’ve just done something unusual maybe.” And then (SNAP) it passed and the meeting was over. And, “Thanks for coming in,” and– and Priebus walked me out. It was like–

If only he had said “Yep, America sucks too,” he might still be FBI director today.

Comey doesn’t say when exactly he turned on Trump — presumably when he got fired, given his public silence before that — but the following is a possibility. He’s describing the pre-inauguration briefing here at which James Clapper told Trump and his team that they had high confidence that Russia had interfered in the campaign but had no judgment as to whether that affected the election. According to Comey, the only thing Trump, Pence, etc, were interested in upon learning that was how to spin the information to minimize the impact of it on public perceptions of Trump’s legitimacy:

And then the conversation, to my surprise, moved into a PR conversation about how the Trump team would position this and what they could say about this. They actually started talking about drafting a press release with us still sitting there. And the reason that was so striking to me is that– that’s just not done…

No one, to my recollection, asked, “So what– what’s coming next from the Russians?” You’re about to lead a country that has an adversary attacking it and I don’t remember any questions about, “So what are they going to do next, how might we stop it? What’s the future look like? Because we’ll be custodians of the security of this country.” There was none of that. It was all, “What can we say about what they did and how it affects the election that we just had.”…

I felt this effort to make us all– and maybe this wasn’t their intention, but it’s the way it felt to me, to make us all “amica nostra.” We’re all part of the messaging, we’re all part of the effort. The boss is at the head of the table and we’re going to figure out together how to do this.

The reflexive response to ominous news of foreign meddling by a narcissist who got famous on television was to wonder what it might do to his image? You don’t say.

Coincidentally, WaPo has a worthwhile piece out today about Trump’s tortured relationship with Russia over the first 15 months of his presidency and how he’s increasingly given ground to the many hawks in the West Wing, however reluctantly. He cursed his aides for pushing so hard to have the U.S. take the lead on expelling Russian diplomats over the Skripal poisoning — but he went along. He complained that the U.S. has no business in Ukraine but approved sales of antitank missiles on the theory that that might bring the war there to a quicker end. He bombed Syria three days ago despite Putin’s obvious opposition. Whatever his personal feelings about the hostile measures his administration has taken (“The United States essentially has three Russia policies: the president’s, the executive branch’s and Congress’s,” said one analyst), the fact remains that he’s allowed them to be taken. But even his aides, reportedly, try to steer clear of discussing Russian campaign activities with him knowing that he views that as tantamount to echoing the Democratic line that he didn’t win fair and square. Under the circumstances in January 2017, with liberals chattering about mounting an electoral-college revolt against him because of Russia’s activities and the media trumpeting the fact that he’d lost the popular vote, is it really that strange that Trump’s first reaction to Clapper’s report would have been to worry about his own legitimacy as an incoming president?

Here’s Comey talking about his exchange with Trump about the “killers” in the U.S. and Russia government. He was glad in hindsight that he challenged him, he said, since the hostility from Trump put the DOJ at arm’s-length from the president, which is where it’s supposed to be.