Why is someone a pathological liar?

Because they have lied so much that they have lost all conscientious pangs and are callus to doing wrong of this sort.

So that above answer was completely conceited and wrong. I am a pathological liar. Therefore I am the best person to tell you about pathological liars. Right, pathological liars lie because they find it too uncomfortable to tell the truth, much like how an honest person finds it hard to lie. However, we lie about the most mundane thing sometimes. I even make up stories to win an argument. Also, most people will tell you that we lose track of our lies. For me that is not true, I have an excellent memory capacity and therefore can remember nearly every important lie I've told.

Furthermore we have not lost all conscientous pangs and we are usually not callus. This person was obviously thinking of a sociopath which is completely different to a pathological liar. We don't lie to advance our own goals unlike sociopaths, we lie because it feels comfortable for us.

An example was today in my class. I was asked if it was my birthday due to a prior conversation with a friend. I just said yes out of instinct (even though it wasn't). Now there is now harm done in that lie. I got sung happy birthday and nothing bad happened. We have spent so much lieing that it is second nature to us. I hope I have helped you understand.