Did you actually used to believe lying to people was wrong?

I had a cousin who was a narcissist, when I was a teenager (years ago) I told him that lying and cheating people was wrong, and he straight up said 'why is it wrong? it works'. Didn't really believe him, left the discussion, he was doing fine in life, successful in everything he did. The part that matters is that every relationship he ever had, was completely fucked up, and he lied to his business partners and customers with no remorse, stole from them when he could, cheated on his girlfriends, but other than that he had a happy life. <br><br>What I'm trying to say is that I was really stupid to believe we were living in a world where the rules were 'don't lie, be honest, don't steal and don't murder' like the ten commandments or something. Back then I really was living in a fantasy. I had to go through a lot of shit before I realized this. How did you get to this conclusion, what changed it for you?