Honestly not even mad when this happens. It’s a bit of an ego boost to be regarded as the gorilla in the playground, and if I’m actually at that level and not merely lucky, it’s great practice.
It’s why I don’t like playing competetive board games. The one time I managed to win a game was because the guy who’d do that the most often didn’t realize how to counter my character (and it isn’t immediately obvious who’s winning until points are done) and man did he fucking moan about how my character was op and no one could stop her and I’m just…you didn’t try. Quite easy to make her go doom spiral but yes, bitch more about you failing to ruin my night.
That’s why I refuse to play with people who are bad sports (bad losers/winners). I understand people who don’t enjoy competition, but that doesn’t sound like your story. I enjoy healthy competition, but that person sounds like someone who just enjoys winning, and that’s just toxic.