i kept racking my brain about the conundrum you inquired about, but have to give up. maybe you better ask the poor souls who are afflicted with that particular disorder.

To boost their little ego. Low self esteem and zero confidence plays a huge part on why some people are like that.

Animal instincts. Humans are animals after all. Status and admiration increases chances of reproduction and attracting sexual partners. You see it all the time in the animal kingdom. Humans are still animals after all, so yes, it is still effective to some extent in human society also.

Some are sociopaths. Some are simply egocentric and narcissistic. Some try to hide an inferiority complex by trying to demean and control others.

Thanks everyone for your comments.

I wish I knew.

More often than not it's because they secretly feel "less than" and one way to remedy that is to diminish others. Sometimes they have weak arguments and so pursue character assassination or other forms of ad hominem in a vain attempt to diminish the credibility of their opponent.

Then there's just the people who get off on being nasty to others.

Because they feel wanting.

Survival of the fittest mixed with sentience makes for what you're seeing.

It’s a ‘power’ thing, an evolutionarily compulsion to always look good and never lose face. Similar to rejection, feeling weaker, less intelligent etc than other people hurts the ego and makes us feel bad.

One can get over it to a certain extent. For example: if you are actually superior in a certain way (a dreadful word but I’ll use it here anyway) to someone: maybe a tennis coach who’s much better than his pupil, then you don’t necessarily have to prove it, and can instead put all your focus on the pupil and not you.

People can feel however they want as long as their actions are benign

it's there nature

When you address me as your one true Empereor then I may let you know ......

Insecurity.