There's this principle I learned from my parents; they used to tell me that if someone is winning in any form of competition, it's not right to praise or announce your success when your friends are not part of the success. For example, if Mr. P places a bet with his friends and his friends end up losing their bets while Mr. P's is successful, it's not wise for Mr. P to start announcing his huge win in the presence of his friends, who are still feeling unhappy about their loss.
Your parents principles are gold. That was them instilling in you moral uprightness from childhood. There are many different variants of this principle that you were taught. The lesson is empathy. If you put yourself in their shoes, you will not want to them to "celebrate" while you are feeling bad from your loss. It's ok to be honest it's your friend and your friend or relative will be glad that you shared your experience so they will not get astray, sharing is caring especially for people you care for.
My respect for my friends will increase if they are honest and open with me instead of acting like the Messiah. So also should he do. Sharing these experiences helps because the more they are bottled in the more damage it does and it will grow worse. 
