By this point, almost 6 years into Trump's presidency, I'm almost used to his latest outrage of the day. I'm still not used to him using the bully pulpit literally, like calling a reporter (Bloomberg News White House correspondent Catherine Lucey) a "piggy" and routinely publicly insulting journalists to their faces, calling Mrs. (Heidi) Cruz ugly, and coveting his name on an aircraft carrier to the point that his sycophants are talking about renaming one originally intended for a black WWII hero, Doris "Dorie" Miller. During his first term, there was a notorious attempt to keep a destroyer named after McCain (with whom he feuded) out of port during a Trump visit to Japan. More recently, Trump tweaked an unattributed 1948 Life Magazine ranking of Presidents, putting himself at the top. He has become the first POTUS to put his signature on fiat currency. Trump has used the Justice Department as an extension of his personal legal staff, still trying to reverse his E. Jean Carroll sex abuse and/or defamation convictions, arguing a POTUS has immunity from defamation laws. {You cannot argue defaming a private citizen is a protected Presidential duty.) He has also used Justice to go after political enemies like Comey, Leticia James, Bolton, and others. Trump has routinely tried to use his control over the FCC to go after late-night comics like Colbert and Kimmel, and more recently the NBC MTP moderator Kristen Welker, over saying his record of successful partisan endorsements is mixed. Then there is Trump's obsession with tacking his name onto the Kennedy Center for the Performing Arts.
As I've tweeted, I don't necessarily fault Trump for having an inflated ego. I think having a healthy self-image is a key ingredient for displaying confidence in leadership. I do have some broad principles, though. The first relevant one involves pragmatic leadership. One thing that drove me to support George W. Bush in 2000 was his bipartisan record as Texas governor. When I lived in Texas as a young adult, Texas had been a solid Democratic state for a century; John Tower gained a foothold by succeeding LBJ in the Senate after LBJ became VP under Kennedy. Years later, Clements served nonconsecutive terms as governor. Bush succeeded Clements after an intervening term. Bush had to work with a Dem-controlled House and a Dem-controlled Senate (until the 1997 election). Thus, Bush had to work pragmatically and bipartisanly. By the time of the 2000 election, I was fed up with the partisan warfare on Capitol Hill, and I thought Bush's leadership style was a necessary prescription. That was probably an unrealistic expectation. I never expected Bush's nation-building in the Gulf region after Bush relevantly criticized Clinton on Eastern Europe and the hard-won balanced budget under Clinton vanished. The GOP lost its way in Congress under Bush; I think my jump-the-shark moment was when a GOP senator threatened to resign when the Bridge to Nowhere in Alaska funding was challenged. Still, although I never supported Trump, I thought his main selling point was negotiation and deal-making skills, and that he was a former registered Dem and not a political ideologue; Trump might succeed where Bush had failed. That completely evaporated when I saw Trump, despite thin majorities in both chambers of Congress, playing political hardball, even constantly demanding that the Senate retire the filibuster, never mind using the Justice Department to go after his political enemies.
The second point is Trump's inconsistent principles. Notably, Trump had criticized Bush's Gulf region wars and used an America First theme to discuss foreign policy. In fact, Trump had accused Obama of plotting a war on Iran. But he was hardly a principled noninterventionist; true, he threatened NATO, but that had more to do with what he saw as European allies freeloading at US expense. He did not shut down the Afghanistan War; In fact, Trump not only ramped up undeclared drone wars, but he relaxed engagement policies aimed at minimizing and reporting civilian casualties. Via Google AI:
Yes, Donald Trump significantly ramped up the use of drone strikes and loosened military restrictions during his first term in office. [1] (https://www.merip.org/2018/02/trumps-drone-surge/), [2] (https://truthout.org/articles/trump-has-pushed-ahead-with-drone-strikes-putting-us-citizens-in-the-crosshairs/)Increased Strike NumbersTrackers and foreign policy organizations, such as the Council on Foreign Relations, noted that the pace of targeted strikes and drone operations heavily outpaced the early rates seen under the Obama administration. [1] (https://www.cfr.org/articles/not-so-peaceful-transition-power-trumps-drone-strikes-outpace-obama), [2] (https://finance.yahoo.com/news/trump-using-deadly-drone-strikes-191800659.html)Data compiled by groups like the Associated Press and Bureau of Investigative Journalism showed that strikes in places like Yemen surged dramatically during Trump's first two years compared to previous years. [1] (https://chicago.suntimes.com/news/2019/5/8/18619206/under-donald-trump-drone-strikes-far-exceed-obama-s-numbers)Assessments by publications like Middle East Research and Information Project indicated an overall record increase in munitions and air combat deployment across Middle Eastern conflict zones. [1] (https://www.merip.org/2018/02/trumps-drone-surge/)Policy and Rule ChangesLoosened Restrictions: The Trump administration lifted strict Obama-era rules that required a "near certainty" of zero civilian casualties before authorizing a strike outside of conventional war zones. [1] (https://truthout.org/articles/trump-has-pushed-ahead-with-drone-strikes-putting-us-citizens-in-the-crosshairs/)Active Hostilities: Parts of countries like Yemen and Somalia were designated as regions of "active hostilities," giving military commanders and the CIA broader and faster authority to launch attacks. [1] (https://www.nbcnews.com/news/military/trump-admin-wants-increase-cia-drone-strikes-n802311), [2] (https://truthout.org/articles/trump-has-pushed-ahead-with-drone-strikes-putting-us-citizens-in-the-crosshairs/)Reporting Rollback: In 2019, an executive order removed the requirement for U.S. intelligence agencies to publicly report civilian death statistics resulting from drone strikes outside active war zones. [1] (https://truthout.org/articles/trump-has-pushed-ahead-with-drone-strikes-putting-us-citizens-in-the-crosshairs/)
Not to mention, Trump had appointed neocon interventionists like Bolton to powerful positions. More recently, Trump joined with Israel in launching an unprovoked war on Iran.
It's not the only instance where Trump's policies have shown inconsistencies. Trump's trade wars have been based on net trade deficits. The US has enjoyed a surplus with Brazil, but Trump slapped a heavy tariff on Brazilian exports, not for intrinsic protectionist reasons, but out of outrage that Brazil has prosecuted its Trump ally predecessor, Jair Bolsonaro. Then Trump, in a desperate move to offset sky-high beef prices, cut a special deal on Argentinian and Brazilian beef, which his ally farmers/ranchers opposed. (The quantities are insufficient to materially affect prices.)
A third point is Trump's undisciplined, unconstitutional power grabs. Take, for instance, birthright citizenship. The 14th Amendment not only unconditionally affirms jus soli, but under Title 8 of the U.S. Code, Section 1401, Trump had no authority to issue an executive order redefining citizenship rules. Then there have been his manic, unprovoked trade wars that have roiled global markets, increased economic uncertainty, and exacerbated inflation for consumers and businesses, not to mention retaliatory tariffs hurting American exports. Tariffs are taxes, explicitly under Congress' power of the purse. Trump has been trying to use old laws in an unprecedented way, not to mention that Trump's actions violate GATT and WTO, which were ratified by Congress.

Trump has also abused his authority in other ways that violate the First Amendment. For example, after Trump absurdly renamed the Gulf of Mexico, the White House barred the AP, not recognizing the change, from pressers. (Don't get me started over his renaming Lake Ontario in his latest trade war with Canada.) Trump has tried to use the FCC and merger review authority to go after network reporters and late-night comics. As described earlier, Trump (trying to manipulate the independence of the Fed) has gone after Federal Reserve Governor Lisa Cook and his political enemies, explicit violations of the rule of law.