At least in my experience, g*mers, and weebs even moreso, were outsiders in their adolescence for whatever reasons, and were more likely to forgo more typical interests in favour of two hobbies that didn't need IRL social interaction, and tended to be more online in an era where many people didn't use the internet much. This view of themselves as separate from most people lead to disdain/hatred of "normies", and when you define yourself around hate, you end up being open to reactionary ideas. Additionally, 4chan was a pretty big site when it came to both anime and video games, and many former users would bring their reactionary culture with them into newer online communities, where they have continued to propagate.