Lies can kill any relationship

First of all, why do people lie? There are white lies, told to not hurt someone else's feelings or to protect... regular lies... lies said to hide wrongdoings... things which one knows will get them into trouble... things which will jeopardize their relationship... things that would stir up another argument or fight... and many many more...

Yet... why do people still lie? Is it due to selfishness? no respect? wanting the fun but not the responsibility? dare to do but dare not admit? influenced? character of the person? what is it??

I guess... only the liar will know and no one else...