You may be more pessimistic or nihilistic than me. Our big brains might indeed be immensely destructive and self-destructive, but because they're anomalous, they can also be creative. I don't have a crystal ball for predicting the far future, but it's fun to ponder the constructive possibilities, too, such as transhumanism.

For me, our anti-natural tendencies support a kind of humanistic ethics, but I temper that with cosmicism (with a horrific view of the universe as an inhuman, absurd wasteland).