Other people’s prejudices are not your fault, not your responsibility, and none of your business. Just because someone dumps their garbage at your feet doesn’t mean you have stop and pick it up. Whatever they said is only a problem if you believe it. If you don’t, then don’t rent them space in your head. You have no control over what other people do. Which means you have no responsibility for what they choose to do.

Is this really something to be mad about?

I'm quite certain that "dude" is now a commonly used gender neutral term. Also who tf is looking at people's profile bios in discord? My profile pic is Christopher Lee and I don't expect people to address me as "Sir Christopher Lee". Edit: I probably should make my point more clear so as to not get misconstrued. My point: So what? Yes, yes I am aware that what happened to you sucked. But come on, it's a random on the Internet and all you've done on your part is saying "their motives were evil and they're also racist". What am I supposed to do with that? That's so little information on the matter and I'm not sure what you want, except attention. You want my sincerity? Well you're going to have to earn it. You have quite the reputation and so I'm not just going to take something at face value. Explain the situation, and why its negative impact is worthy of sympathy or why should I respond at all?

Sorry that happened

Ok, Billy. Edit: we all know you're a sentient meat wad, stop pretending.

OK.

So from a position of ignorance I ask: Is stuff like that just bound to happen? Like in discord. If I don't know you and you don't rep pronoun gang, I'm probably making an assumption based in vocal tone. Not to be malicious.... just... working with what we've got.

Probably not malicious as it’s not a face to face encounter and it’s a 50/50 shot of getting it right.

Welcome to my life. Im at the point where I just don’t give a -blam!- anymore

Was it malicious or a genuine accident?

Most likely it was just an accident, and in that case, simply correct them and let it go. It can be an easy mistake to make. It's only a problem if it happens repeatedly, and intentionally.