In short, it's fun.

I think because it's more challenging and keeps my mind occupied in the same way that playing chess or poker does. And if I'm more engaged in the discussion, I end up learning more about the topic as a result.

Moreover, there are a lot of social expectations when it comes to close relationships. Which I understand on some level and can navigate somewhat. But it feels a bit like I'm walking on eggshells with most people. With more antagonistic relationships, there's less expectation of that, so I don't have to restrain myself so much and don't have to perform the normal politeness. I can be a little more myself, essentially.

And anything*. The topic is less important than the desire to win.

*within reason