The thing about Trump is:
To many people he comes across as aggressive, bombastic, sexist, foul-mouthed, and divisive.
You may disagree, but I am sure you can see that such behaviour might warrant an adverse reaction.
It was interesting to read Hillary Clinton's account of how she used to be "prepped" by her aides for her TV debates with him. As a woman she felt potentially threatened by his mere presence on stage, and one of her guys would "do a Trump" by clenching his fists, leering, and following her around the floor. It was disconcertingly like the real experience, as it turned out.
Even as a bloke I can see how that sort of behaviour and body language might be repulsive.
For many people it is like that: fire a projectile at a wall hard and it may come back at you. It's like Trump: he shoots from the hip, and people shoot back. But he usually shoots first :-)