I think is because they are afraid ... of what?... who knows !!!! Ultimately, everyone acts from his/her own beliefs. ^^

Why do people lie? More of a moral question than a language one. People think that lies are easier than the truth but it is not the case.

To escape from truth - ( I know some people personally who like to lie just for fun ) and that's terrible of course .

because they think that maybe save them from troubles.

'Why do people lie?' Don't you have people around who have lied to you? Ask them. And, raise your hand if you didn't lie once. Or at least, a half lie, which is worse. Don't judge people, each person has its own reasons. We just have to ask 'Why?' But, to the ones who lied to us.