Obviously the recent child internment camp news resulting in Nazi comparisons isn't the first (nor will it be the last) time someone has pulled out that other N word when talking about Trump. This seems to always inevitably devolve into a back and forth argument of those on the left semi-gleefully calling Trump and the right "Nazis", while those on the right take obvious offense to being called something so terrible.
However, I think a real problem is that Nazis are the defacto stand in for fascists, despite there being many kinds of fascists with many that didn't reach the level of "pure evil" that Nazis have come to represent to a modern person.
Personally, I don't think there is a very valid argument to make against the idea that Trump at the very least has fascist tendencies (personally, I'd skip the mealy mouthed talk and just call him a fascist).
These days, calling someone a fascist is a pejorative, but when fascism came about in the early 20th century in Italy, it was merely a political philosophy. It was only the eventual outcome of those original political ideas that gave the term the connotations that everyone (even people who would agree with fascist policies) wants to avoid being associated with. If you strip out all of the historical baggage of fascism and attempt to evaluate Trump and his ascendency as it compares to some generally accepted aspects of the political philosophy of fascism, I don't see how you can come to a conclusion that Trump and his "core" don't at least fall on the spectrum, but I'd love to see counter arguments.
While there is no settled upon dictionary definition of the term, there are some common themes to fascism that are often present that I'm going to use as a summary:
Fascists desire strong central leadership (often eventually ending up as a dictatorship) predicated on a desire for national unity and promotion of nationalist identity.
They believe that this strong central leadership with little (or ideally, no) opposition is necessary to restore national unity and order.
They focus on an idea of a need for "rebirth" of the nation due to perceived community decline, humiliation, or victimhood at the hands of other nations.
Claim to draw their power (and in many cases, do) from "the people" and function as a populist movement, however it is almost always lead by some segment of traditional elites.
Often make use of ethnic stereotypes and fear of foreigners in a desire to strengthen internal unity.
Oppose the far left, have a disdain for parliamentary liberalism and the traditional processes of modern Western government, and often eventually turn on traditional conservatism as it proves unwilling to do what the fascists deem necessary. Draws their primary base of support from those on the far right.
Believe in an aggressive foreign policy in both the military and economic spheres, favoring military and economic intervention, and isolationism.
Working from that list (which admittedly is incomplete and not an in depth view of the various examples of fascism throughout history), I see far too many recognizable patterns to feel comfortable with where our country might be headed. Obviously we're not currently living in Nazi Germany, but many Germans didn't realize where they were headed until it was far, far too late either. Perhaps if there was more of a historical knowledge of the dangers of this type of belief system at that time, the Germans could have stopped things from going so far.
I do not believe that Trump himself would consider himself to be a fascist at all. I think he (like his supporters) would bristle at the mere mention. However, I believe that history is telling us to be wary of the path that we're on, and with good reason.
Given the political climate of the day, I'm doubtful this will generate good discussion, but I wanted to try anyway as this comparison is a belief I've held since ~2015 when I first started seeing videos of his rallies and the rhetoric he was using.