I've been terminally online since 1999. I was there when social media wasn't a term that existed, when everyone communicated on individual fragmented "message boards": Just plain text that you posted for the community to see and, if you were cool, reply to.
I was also there for the rise of imageboards, and of 4chan. And I was into it. Not really 4chan itself; I found it too hectic and, yeah, a little *too* evil for my tastes — at this point in history, there was very little legal regulation on the internet, and they posted *everything* there — but that isn't to say that I wasn't evil. I liked shock humour. I liked sexist and bigoted jokes. I said the N word as if it was a punchline. That's...kind of how things were.
It really wasn't until around '07 or '08 that we, or at least the people around me, started to confront the reality that this was all kind of fucked up. And I actually defended it. I said, "It isn't really racism, it's ironic! It's actually a celebration of how we've defeated racism, how ridiculous racist words and statements seem these days." And I believed it. And maybe that's what it was for me, but of course, I was incredibly wrong, probably the wrongest I've ever been in my life, because that absolutely wasn't what it was for the people around me. People who would go on to become alt-right, incels, and probably what we now call Groypers.
I wouldn't know, because I haven't had contact with these people in over a decade. I'm lucky; I could have fallen into that, too. Now, I can come to the online left as someone with first-hand knowledge of how these reactionary movements start and perpetuate on the internet.