Lying can be a very important skill. For that matter, becoming a good thief can be important. I heard about a Native American tribe where boys had an “invisible” year. For a whole year, no one could “see” them. No one could feed them. No one could interact with them in any way. So the boys learned to steal—an important survival skill.
Lying can be an important survival skill, too. There are times where if you tell the truth, you’ll be killed. Or you could severely damage the lives of others.
Lying is a selfish thing to do. You hope to get away with something that benefits you without others finding out about it. Or you hope to get away with something that may hurt others if they knew. Like others have said, once you start lying, you have to keep on maintaining your story. That can cause a lot of stress.
When you are eventually found out, there will be hell to pay. No one will trust you again. They’ll always wonder if you are still lying. So whatever you’re lying about had better be worth those consequences.