Why must people choose to live in arrogance?

Think at its core is a basic insecurity in which they either have to tear others down or puff themselves up in order to feel good. So when someone comes along to threaten that system they don’t take kindly to it, as you’re trying to take their defense mechanism away.

Because nothing happens face to face any more, it's all text, posts or emails. It's easier to look into a screen than someone eyes.

I want to live in vain, nobody should die in vain

They don't enjoy being told they're not special...

They don't know

Probably a result of the ego.

They shouldn’t get mad, they should just believe that you are wrong. That’s how arrogance works

Arrogance rudeness impolite behavior and belittling someone is all in the mind of few and psychologically it gives them peace of mind.

Immaturity. Bullying.