People forget most of the games you won. They remember how you acted after the ones you lost.

Winning reveals very little, because almost everyone is pleasant when things have gone their way. Losing is where character becomes observable, in whether you sulk, blame, disappear or handle it, and people register that far more sharply than any result. It is the one occasion where your behaviour is genuinely information.

Decide in advance how you intend to be after a bad result, because deciding afterwards is much harder. Say the fair thing about whoever beat you. Then take the disappointment somewhere private, which is allowed and entirely normal.