The feelings of hatred are there to motivate us to move away or avoid the people or things that we believe have the potential of causing us pain. We are all naturally motivated towards pleasure and away from pain.
For example, when a student says, “I hate maths” it means math is a potential source of pain for this student. It may be that he isn’t good at it or that his math teacher is boring- we’re not concerned with why hates math.
What we’re concerned with and know for sure is that math is painful for this student and his mind, as defence against this pain, generates the feelings of hatred in him so that he’s motivated to avoid maths.
Maths causes him such psychological discomfort that his mind is forced to launch the emotion of hatred as a pain-avoidance mechanism to make sure he stays away from maths. Had he been good at maths or perhaps found his math teacher interesting, it’s highly likely that his mind would’ve found it unnecessary to launch the emotion of hatred and he probably would’ve loved it instead.
A student who always wants to top in his class may hate his bright classmates and thus feel uncomfortable around them. On the other hand, he might feel okay when he deals with average students because they pose no threat to his goals.
He may, therefore, criticize you, gossip about you, ridicule you, laugh at you, demotivate you- anything to hinder your progress. He won’t congratulate you or acknowledge the great things you might have done even if he was impressed by them. He already feels inferior and can’t make himself feel worse by praising you.
Haters can’t see you happy and sometimes may even ask you detailed questions about your life just to make sure you’re unhappy and miserable or at least doing worse than them.
When someone acts in a way that we don’t like or does something against our wish, we usually do our best to change their behavior by employing various options. When we are unable to do that, our mind unconsciously makes us hate that person since not getting what we want is painful and the very purpose of hatred is to avoid pain.
If during school you hated a rude teacher who had brown hair and wore specs, then you might find yourself hating a similar-looking person (with brown hair and specs) without understanding why.
This happens because you subconsciously think that the two persons are the same therefore hating one person automatically makes you hate another.