I don't think they hate them as much as dislike, or distrust them. Cats can be aloof and unfriendly, especially to people they don't know. Dogs you can generally tell what they are thinking. Cats aren't as easy. Plus I have seen cats just stare at people, which can make some uneasy and freaked out.
Because some people have allergies and can't have cats because they give them headaches or because a cat is not like a dog that you can train him to pee outside and do his stuff outside it is very hard to get a cat to do those sort of stuff and their urine has a horrible smell that no matter how much you clean the house it will probably still be there for awhile and if he urinates the carpet it would be worst so things like that make people hate them/
Some people have something called Ailurophobia which is extreme or irrational fear of cat. Sometimes there's no reason why, they just hate them. Some maybe had a bad experience with a cat when they were younger or something or many other reasons. I know a few girls who are seriously afraid of cats, birds, dogs, snakes, and other types of animals.
SOME people hate cats and other animals to justify abusing them> Serial killers in the making>>> Animal abusers are as foul as they come... Don't let me catch anyone abusing a animal in public or private. !!!!
With some it's just ignorance. With some it's allergies or cat hair on their clothes, some it's because they can't control them as easy as dogs. An animal is an animal domesticated animals give unconditional love & need love in return. Bless!!!