Hiya, have you ever heard of CLS, Compulsive Liar Syndrome? It could be an explanation for your behavior, as the reason for why they are lying, simply is because a habit has set in. Which like any bad habit, is hard to break.
Some of the symptoms include lying about anything and everything, make up new stories to cover up their lies, suffering from low self-esteem etc.
If you wan’t to know more about it, you can do some research and also look at this webpage: