Actually I think many people have very good reasons for disliking Trump.

Almost all Americans -- most voters -- are good people. Sure there is the angry mob effect which might have some influence, but for the most part they are good people and want the best for Americans and America. Trump supporters, Bernie supporters, even Hillary and Cruz supporters.

I don't blame them because the establishment have waged incredibly sophisticated and successful psychological warfare against them for decades. The media on both sides are completely owned and run by and for the establishment, so are the politicians. It's easy to get caught up in the narrative and fall for the divide and conquer, and false choice, and all the other strategies they use. I have, and probably most of us here have at one time or another.

Now for the people who research more closely and have the information available but still hate Trump, I think they tend to have good reasons for it.

Establishment - Globalists, media, politicians, bankers, etc. for obvious reasons.

Conservatives - I think many of them fear change to the point that they fear a change of tactics even after it has become clear that existing tactics are failing. Many others don't want to move away from religiously motivated social policies.

Liberals - Despite their divisive rhetoric and discriminatory policies, they are the self proclaimed "solvers" of all social problems. And people believe it, for some reason. They claim to be the only ones who can help the poor, improve race relations, improve the lives of women, etc. However as is the case with conservatives and their hollow claim to being superior economic managers, it's clear to see that liberal politicians don't improve any of these things. Not surprising when it is in their own interests not to solve these problems. The biggest fear they have is that Trump's policies will actually improve these problems. That putting Americans first, using inclusiveness and fairness and real equality, will actually start healing some wounds and improving people's lives. It seems like common sense, but if the simplest and most obvious approach is found to work, a lot of liberals will be out of a job.

The same goes for conservatives on economics too, btw. They don't want Trump to show people that a politician putting his country first is no crazier than a CEO putting his company first, or a person putting himself first. It's basic economics. Free trade is not always the best solution when the countries you are trading with are competing against you and putting themselves first.

So it's fear, really. But it's not fear that Trump will ruin the country for these people, it's actually fear that he will succeed even half as well as his goals.