It's basically a culture of trolling people and making lots of overly sexual and racist jokes. The porn on his phone was "nude anime girls with MAGA hats". A lot of 4chan users seem to be Trump supporters. I'm not sure what percentage are actual Trump supporters, versus people who just want to troll the US with memes and watch the world burn.

One of the email domains is "tfwno.gf", which means: "That feel(ing) when (you have) no girlfriend". Depression and loneliness is a common theme, so there's a lot of lonely people taking out their frustration. There's also a lot of pretty normal people who just enjoy being rude and gross for no reason.

4chan can be a pretty dark and weird place. But I've heard there can also be some fairly positive sub-communities and good discussions.