If you didn’t think people can change, you probably wouldn’t spend as much time arguing with people on the internet as you do. Not really much point in doing that since you’re not going to change their minds after all.
But even if you genuinely don’t think people are capable of improvement, I think it would still be worthwhile in a “know your enemy” sort of way.
My dude, what the actual fuck are you on about?
“Know your enemy” isn’t a saying about peaceful turn-the-other-cheek, love-thy-neighbor, forgiveness bullshit
It’s about knowing how and why they fight so you know how to defeat them.
You can’t and won’t win over every individual Nazi or klansman and make them see the light, but each one you do is one less enemy on their side and one more ally on yours, and my talking to them you get a better understanding on how to beat them.