Person A plays a game of chess and loses. Then he wont try again, because "I'm not good at it". Person B plays a game of chess and loses. Then he loses again.

Person A plays a game of chess and loses. Then he wont try again, because "I'm not good at it". Person B plays a game of chess and loses. Then he loses again. And again. Then he wins. (Then he finds a stronger opponent and starts again.) Person A didn't gain anything, while person B found a new hobby that he enjoys spending his time with. Of course, this example only works if both were interested in chess and A really gave up, rather than just figuring out that chess isn't his thing.