People who can’t do better do not decide to be obnoxious liars, they simply can’t do better. It is their twisted mental constructs which control them.
They don’t appreciate they are lying, they actually believe the lie as they say it. They don’t see that they are inconsiderate because they don’t know other people are alive.
It is not that you can speak to them and indicate their anti-social behaviour and they will listen or even give you a second of thought.
They do not perceive their behaviour as erratic or bad tempered or cruel and nothing you say or do will change that.
You must recognise that this is not a person to whom you can state the obvious and they suddenly perceive their fault, this is a person who is locked into their selfish persona and will never leave it.