Ruth Ben-Ghiat is a frequent contributor to CNN Opinion and a professor of history and Italian studies at New York University who writes about authoritarianism and propaganda. Follow her @ruthbenghiat. The opinions expressed in this commentary are solely those of the author. Read more opinion articles on CNN.

(CNN) Here's a secret about authoritarian-minded leaders like President Donald Trump: They are their own best friends (they usually have few real friends), and they are their own worst enemies, especially when things are not going well for them.

Ruth Ben-Ghiat

This is Trump's current situation. Revelations that he tried to get Ukraine President Volodymyr Zelensky to investigate Democratic presidential candidate Joe Biden and his son Hunter Biden have led to the House Democratic leadership to announce the start of an impeachment inquiry. Trump has reacted predictably . "Another Witch Hunt!" reads one of a flood of Tweets on the subject.

Yet Trump has brought this situation on himself by demanding that Americans, including those who work in the White House and in the federal government, accept his autocratic personal style of governance, scorn for the rule of law and insatiable need for loyalty to him over duty to country. For at least some in the government — like the whistleblower and the intelligence community's inspector general — Trump's actions warranted sounding an alarm.

This is a predictable outcome for a leader who has been following the authoritarian playbook from the start. Authoritarians view public office in an entirely proprietary manner: It is their vehicle for power and enrichment for them and their family. National security, economic policy, and foreign relations must be subordinated to their personal agendas. In Trump's case, his agenda is a combination of making profits for the Trump Organization — for example by allegedly pressuring the US Air Force crews to stay at his Turnberry resort in Scotland during refueling stops (something Trump has said he knows nothing about) — and fending off anything and anyone that might threaten the consolidation of his power. This includes Biden, a man he evidently feels might take him out of office in 2020.

Leaders like Trump behave in predictable ways and follow foreseeable patterns as they use public office to further their private goals. First, they need co-conspirators: an inner sanctum of loyalists who will do their bidding and keep their secrets. This is why they often hire their own family members and why they fire so many other people — it can take a while to find the right individuals to infringe democratic norms for them. Trump now has the man he calls "my attorney general," William Barr, who gave misleading information about the Mueller report to protect his boss and is cited repeatedly in the whistleblower's report as being involved (along with Trump's lawyer Rudolph Giuliani) in the request for a favor from the Ukrainian leader, although the Justice Department released a statement denying that Barr had any contact with the Ukrainians.