Lets see, in the last 2 centuries humans have: Devoted years worth of total resource production to kill each other by the millions over a few square miles of r

Lets see, in the last 2 centuries humans have: Devoted years worth of total resource production to kill each other by the millions over a few square miles of resource poor land. That was such a popular hit that we threw a sequel that was even more costly. As a result of the sequel we had several major empires devote trillions of dollars to making sure that we could annihilate our own species just in case one of the others also tried to annihilate the species first. This caused the collapse of at least one empire. People regularly call for the use of these annihilation weapons and it's sheer dumb luck that it hasn't happened yet. Speaking of annihilation - there have been several large scale attempts at exterminating all humans that fit xyz criteria in the last century. Mostly these are not based on anything other than "exists with DNA slightly different than our own". It seems likely that "exists with way different DNA" and even "exists with a different building block than DNA" could be used as criteria. If you don't limit yourself to intelligent species, humans have carried out large scale attempts at exterminating several native species. Some I'm aware of in the last couple centuries: Wolf eradication programs paying bounties per dead wolf. Same for the american bison. (this one is special because it was also intentionally an attempt to genocide native folks by starvation). The "smash sparrow" campaign in china - kill all the sparrows because of a misunderstanding of what food they eat. I guess I could buy your premise that humans wouldn't participate in the dark forest for logical reasons is semi-believable IFF we ignore the things humans actually do.