Hardcore gamer = someone who plays only cinematic grizzed white dude games and/or military fetishizing FPS
Casual gamer = anyone that is not a 15-25 yo male, and/or plays anything outside of the previously mentioned games, especially if those games are colorful.
So basically the gaming community is full of gatekeeping, misogyny, toxic masculinity and general chuddery. They make sure they're the loudest voice heard when anything about games is talked about, and won't be happy until all games a homogenous stream of bland, hyper-realistic but with a grey filter slog of mindless action with no heart or soul. And don't you dare force them to read any dialogue or story.
Children (overwhelmingly boys) who played vidya games were nerdy. There was a brief period during the Pac-Man era when vidya games were for everyone, and soon it went into hardcore weirdness. Games got hard and unless you had the patience to play again, and again, and again, and again...you can forget being a part of the crowd. Games with 45 levels when nobody ever got past level 4.