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.
"Hardcore gamers" = the people who had enough money and free time to have a console (or two) and buy and play all the big releases. This group is mostly white, male, decently wealthy, and reactionary (in the same way any given white petit bourg is). The people shaping the game industry range from sicko libertarian dipshits (Carmack) to sicko capitalist [redacted] (Bobby Kotick). It hasn't ever been "good" tbh.
Maybe not, but it's sometimes been not as bad. Contemporary monetization/habit-forming trickery in the game industry is refined from decades of deliberate research to make it as ruthless as possible.
As much as I appreciate the convenience, I'll also say that every step away from "gaming as a social activity" has made it worse. I'm at least old enough to have seen the changes from arcades to inviting people to your house to play a console to online multiplayer and it all gets weirder at each step.
No more LAN support in games since like the mid 2000's :(
G!ming as an illusory parasocial activity has been pretty fucked up. Narcissistic celebrity I N F L U E N C E R S siccing their fake-friend fandoms on each other and sometimes spouting nazi shit for funsies are terrible.
Importantly, also socially maladejusted enough that playing those games became their primary identity
The social maladjustment largely follows from the traits previously listed. I can speak from experience.