I have known such people in my lifetime. Some people have practiced lying to the degree at which they can barely decipher what is true from what isn't anymore. The truth becomes that which is most convenient for them. They actually do believe their own lies, that's how they sell it so well. The little voice in their mind that helps them sort truth from lie, right from wrong, they've all but murdered that thing.
I have known such people in my lifetime. Some people have practiced lying to the degree at which they can barely decipher what is true from what isn't anymore. The truth becomes that which is most convenient for them. They actually do believe their own lies, that's how they sell it so well. The little voice in their mind that helps them sort truth from lie, right from wrong, they've all but murdered that thing.