Well it's certainly a nuanced issue.
There are obviously some instances in which high level expertise in a particular field is definitely preferable.
But there are legitimate complaints of elitism that could be levied towards the media elites for example. The MSNBC Freudian slip comes to mind "he [Trump] is trying to control what the people think, and that's our job." The way a lot of them carry themselves as if they are the gatekeepers for what information people should be allowed to know and what viewpoints are and aren't acceptable. Their willingness to lie about someone like Trump (who honestly you shouldn't need to lie about to build a case against) or even someone much more moderate in view and temperament like Jordan Peterson. Or when you look at how many time the Wall Street Journal and other mainstream media outlets have directly targeted YouTube and Pewdiepie in order to directly attack the income of alternative media outlets that are outcompeting them. Or when they dial everything up to eleven and make all these ridiculous clickbait news articles in order to get views and money in a dying industry.
Some people, rather accurately, see the mainstream media not as an objective voice or even the voice of the people sticking it to power. But rather the mainstream media largely acts like its own elite class acting in its own class interests.
Or what about Hollywood? There have been enough award shows in recent years for people to see them mostly circlejerking each other, virtue signalling, and acting as if they are at the cutting edge of the moral salvation of civilization, all the while acting like all those who disagree with their very particular moral view are just a bunch of ignorant hateful rubes.
Or what about the tech elites? A large number of people who in the wake of the 2016 election have said free speech on the internet is outdated and allows the spread of views they don't like, with Google releasing the "Good Censor" memo, and leaked conversations before the election about how to censor or downplay right-wing speech on their platforms, or even the conveniently synchronized removal of Alex Jones (who I don't even like mind you) from multiple platforms in the same day. Again these are people with an agenda who view themselves as gatekeepers for what people should be allowed to talk about and what information and viewpoints they should be exposed to.
And then of course, there's the university elites. Particularly the ones in the corrupt social "sciences" like sociology, gender studies, ethnic studies, basically all of the grievance studies who speak as if anyone who isn't invested in their specific worldview belongs to the evil power structure which has been the cause of all of humanity's problems. They are using taxpayer money and their status as professors and "experts" to peddle this broken ass view of morality which shifts the burden of moral responsibility from each individual to only "the privileged" and shifts basic empathy and the idea that one could have problems from every individual to only "the oppressed." These are perhaps the most insufferable of them all, they appoint themselves gatekeepers not of information but gatekeepers over who gets moral consideration, and in their gross condemnation of society as a whole despite all it has given us. And anyone who disagrees with them is either malicious or just hasn't been taught in the great intellectual pursuit of "critical theory" or "intersectionality."
Just as a recent example of the influence of these grievance studies, media elites, cultural elites, etc. they were able to get Baby Its Cold Outside banned from radio stations. When polled however, roughly only 5% of people actually found this song problematic while 95% of people were just fine with it, meaning 5% of the population was able to dictate what the other 95% of people were able to enjoy.
It is not competence (high level scientific expertise) or success (wealth) that primarily drives this disdain of "elitism." It's this smug arrogant self-congratulatory almost messianic attitude that a lot of these elites hold in their inappropriately self-appointed duty as gatekeepers over the morality and dialogue of society that people take issue with. That they operate as part of this cultural hegemony that largely tries to hold its power through gatekeeping and creating and enforcing an in-group out-group dichotomy between the people who act in their interests and the people who are deplorables.
I'm a Christian, but I'm not going to pretend the church for example has never overstepped its bounds by acting as a hegemonic police of vice and virtue. And it has received a lot of criticism for exactly that reason. Some of that criticism even exists in the Bible with Jesus's criticism of the arrogant self-congratulatory elitist self-serving attitude of the Pharisees (the religious elites of his day). Sadly a decent amount of what came after Jesus's time was a reflection of the issue he originally had with the pharisees. The church has acted as the gatekeeper in shutting down dialogue it doesn't agree with, a lot of people fled to America to escape the hegemonic influence with the church of England, and there has been struggle in the US between a lot of people and churches trying to cement influence in the political system. Even though I am a Christian I recognize a lot of this criticism as legitimate.
The problem is these new cultural elites have become something of the new Church, the new police of vice and virtue in some sense to whom a lot of the criticisms that could be appropriately applied to the church in a historic context could also be applied.
And herein lies the heart of Trump's charisma. He is not willing to be controlled by this hegemony, he is willing to call out the media, he is the figure who has drawn the primary ire of this hegemony and these elitists so many people take issue with. And ultimately when Trump insults or talks down to someone, it is usually one of these people, or a very specific person who is in a position of prominence who is opposed to him. What people don't hear when he speaks is Trump calling half of the nation deplorable, or implying working class citizens are just a bunch of ignorant rubes who need the enlightened guidance of people like grievance studies professors to change their dinosaur ways or whatever.
People don't consider Trump an elitist because of his wealth or status, because those aren't the things that draw the criticism of elitism to begin with.