First, they learn to enjoy life. Play chess is having fun. Chess players love to have fun. What will kids do between rounds? they play blitz or bughouse. They will laugh and they will run around if allowed.
Second, they learn "to be not afraid of losing". They have been beaten, and will be beaten again and again, but they always come back and fight another game.
Third, they learn that success comes from hard work. The more you work, the better you will be.
A chess game is like life, and life is like a chess game. If they have learned these three, their chess tuition has not been wasted.