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.
It was weird seeing the reaction to Demon Souls release compared to Dark Souls. The same people that were complaining Demon Souls was too difficult were all suddenly like "git gud casual" to people that felt the same way about Dark Souls.
To be really fair a lot of demon souls difficulty is straight up punishing like halving your hp, where as in dark souls your potions refill after you die (i know theres that bs frogs that literally reduce your hp but still they were proven to be unpopular was removed)