People smarter than me have written long explanations of the connection between gaming culture, white male fragility, Gamergate, 4chan, the alt-right, and Trump, so I'll just sum it up briefly:
1. Video games have traditionally been presented as a "male" hobby. Young girls are dissuaded, by culture, their parents, and male gamers, from playing video games. Many women do end up playing games, but they aren't the hardcore types who populate gaming forums
2. As a result, online gaming communities end up being overwhelmingly, or even entirely, male
3. In the late 90s and early 2000s, various politicians sought to ban or restrict violent video games. The gaming community and gaming media unanimously condemned these efforts and were, seemingly, on the same side for many years
4. Young men who play enormous amounts of video games lack the social skills to make friends or meet women in real life as they enter their teens. Severely socially stunted, they retreat into their online, male-only communities, becoming angry and resentful at women
This is where it ended, for the most part, until 2012-2014, when the following things happened:
4. Social justice issues became more a more prominent focus of the gaming industry. The harassment wave aimed at Anita Sarkeesian ended up being condemned by a number of gaming media sites (though not nearly enough), leaving many male gamers with the impression that the media that previously aided them in their war against Jack Thompson had since been infiltrated or co-opted by the feminists who supposedly want to destroy video games as he did
5. 4chan's /pol/ board was created and almost immediately became a recruiting ground for white supremacist and men's rights extremist groups, who spread their ideas to unmoderated gaming communities across the internet
6. The Zoe Quinn incident that incited Gamergate was, again, condemned by (most of) the gaming media. The far-right, who had spent decades sowing distrust of the media, encouraged the gaming community to revolt, saying "This is what we've been telling you for years -- they're liberally biased and hate white men"
7. Gamergate was roundly criticized from across the gaming and real-world media and largely failed to succeed in its goals. As a result, its members became further jaded and radicalized, getting hooked into further racism, sexism, anti-Semitism, and other hallmarks of what would become known as the alt-right
8. Trump shows up. The alt-right and 4chan immediately begin to support him
9. Apocalypse happens
