Is it selfish of my cousin if he always wants to win?

Together or to the whole community. I have a cousin who is kind of difficult in terms of behavior. I played fortnite with him so 1vs 1 and after we made a draw he wanted to stop playing immediately. Because he's scared that he'll lose to me. He's not only on it at fortnite but also like Mario kart, Fifa, or the games that you can play in pairs… He's the guy who always wants to win and that's not fun for me when he's like that. Do you also have a cousin or brother or friend who always wants to win? How do you deal with it?

Yes, there are always children (but adults) like that.

Either you stop playing with him or you announce aloud that he has lost anyway if he doesn't want to continue.

Thank you and Merry Christmas