OP: Good question. It has been one of the thing most likely to abandon the forum. While you posed it as a rhetorical question, my assumption is that we can’t just "call on our better natures" to stop being angry. We need to think about why it’s happening.
Here are a couple thoughts. I’m sure there are other reasons. This is a forum and I’m spitballing.
1. We are in a culture where debate is modeled constantly for us on television and other popular media. There, disagreement must be stark and dramatic or it’s not entertaining. If it’s not entertaining, it’s not watchable and people turn away -- and the purpose of TV is to make money. This is why it’s called an "Attention Economy."
So, many of us (consciously or unconsciously) repeat the way we see argument modeled on TV. That leads to anger in our lives.
2. Political debate has become more acrimonious because it takes place largely according to its dominant format -- TV. (See point 1 above.). We create political debates (in tone, form) out of debates about audio. We need to stop doing that. As you point out, we’re debating over luxury items.
3. People ask questions they care about, but these wind up requiring deeper technical knowledge or greater experience than most on the forum have. Yet, it’s no fun to participate in a forum and not write *something.* When people get a bull-hockey answer or a half-assed answer to a question they care about, it annoys them, and they express that. Or -- their question is just ignored. Conflict is now lit.
4. Relative anonymity leads people to say things they wouldn’t in person. For some reason, people think that they can discharge whatever off-forum anger they have, here. Weird thing about anger, though. Unlike the "catharis" theory of anger -- the idea that anger is like pressure that needs to be "released" -- acting in angry ways just makes you (and others) angrier. (See: "Venting doesn’t work even among people who believe in the value of venting, and even among people who report feeling better after venting (Bushman, Baumeister, & Stack, 1999). In fact, venting has the opposite effect—it increases aggression. The better people feel after venting, the more aggressive they are. Venting can even increase aggression against innocent bystanders."
https://alltheragescience.com/commentary/four-questions-on-the-catharsis-myth-with-dr-brad-bushman/ )