Why do some people have total disregard for the feelings of another person?

They are selfish, and lack compassion and understanding. Some have hardened their hearts, or are emotionally unavailable. Depends on what a person has gone through. They need prayer. When we look at people through the eyes of Jesus, instead of the outward facade, we see someone who is hurting, then acting out. It’s really a cry for attention, whether they have to get it through positive or negative responses, doesn’t matter to them. They just want the attention, like a lost child. Someone who needs a friend and help/guidance. However, some just enjoy hurting others. They don’t want help.

they have better things to do

Great question. Don't know the answer but I can confirm for you that it is most people and not just those around you.

Bc other peoples feelings dont matter unless you want something from them

Narcissism.

Sometimes the other person wants too much from them

It never occurs to them to think of other people. Some are just so selfish they never even consider others.

They are cruel if we could understand it,we'd be cruel,too.

they are r-soles

Many reasons. Tact is a dying art. Most it's because of selfishness, I think.

Narcissistic

Lot of people are super shallow.

Narcissistic