Why do some gamers feel it necessary to judge everyone for games they enjoy?

I've been a fan of video games since Sega Genesis. Video games are the main form of entertainment of my life. When I'm not sleeping or at work, I have a controller in my hands or a keyboard in front of me. I love games. Yet, there are people who feel it necessary to be a "hipster" of video games, considering some games too mainstream or too clichéd. Why does it matter? I thought that the sole purpose of a video game was to bring people joy? And these are games that people enjoy, such as COD, Battlefield, Halo, Minecraft, Candy Crush, etc. Whether it be on Xbone, PS4, PC, iOS, or Android, why should any be excluded from the "shpecial shuper shecret club"?

I agree with you some gamers (not all) but some of them are constantly judge others for the way that they play or in their life, i see this especially on youtube.
It's maybe because the video games develop on them a sort of obsession of win, so they put down others, i really don't understand this reaction.

Most gamers who make fun of gamer for what they play are not actual gamers. Cod dose not make you a gamer.

Because people are opinionated and will judge someone no matter what. This is no different from judging someone based on a general first impression, clothing, nationality, the way they talk, etc. Forget games; people will unconsciously judge others based on what they see. We've all done it.

i find that there are valid reasons to dislike triple A mainstream titles. Of course, one of them isn't "because they're mainstream," but because how they are designed in order to become a mainstream game; games like CoD and candy crush don't become popular around the world by luck. However, i reserve my argument for said opinionated "gamers." ultimately, i don't care what you play, as long as you don't bother me.