I don't think comparing Trump to prior fascist dictators convinces any trump supporter to move away from him. We are so desensitized by Godwin's Law: for the last 2 decades, we have fairly consistently heard Bush, Obama, and Trump all compared to Hitler. Further, we envision Nazi Germany as this monstrosity that could never happen again, the German citizens as either horrifically racist or inconceivably gullible. We are not like that.
Guess what? Neither were those Germans prior to being led to that state by a charismatic leader who preached nationalism, grievance, and a common enemy they could focus their hatred upon. I really do NOT think we will become Nazi Germany, I think we have enough guard rails in place and a strong enough counter-balance to Trump's fascist tendencies, and overall most people in this country have it pretty good (much of the grievance is contrived).
But it is hard to not think of the
Kristallnacht when Trump starts hammering his mass deportation plan. There are already paramilitary organizations (analogs to the SA, or "brown shirts") working throughout our country to locate illegal immigrants. In a recent speech, Trump said something to the effect of...we have people ready to take care of these immigrants, and they will be allowed to do so (paraphrased). It was not clear if he was talking about US Law Enforcement, Military, or something else, but it certainly could have been taken as a call to arms for these militias (much like his "stand back and stand by" was in 2016).
I am sure this seems hyperbolic to anyone who supports Trump, and I hope it is truly hyperbole. But it is hard to not see parallels.