why tell people about the secret reward
Just getting the achievement

To get the best achievement in chess.com (imo) you have to defeat a rival stronger than you by at least 100 points, and then write in the chat "Don't hurt the camels". It recognizes your ability at chess for defeating someone stronger than you and your sportsmanship for being gracious in victory.
Is super tricky but totally worth it, and thinking about it, is probably the only achievement I can get and Magnus can't.
Just getting the achievement