You can either throw up your hands or try to come to a greater understanding regardless of whether you call people 'people' or 'evil' or 'crazy', but the last two adjectives are more precise descriptors.
There is no concept of "evil" or "crazy" in objective reality, but there is a concept of "people". The quote reminds us that understanding human behaviour begins by accepting that people do what they do exactly because they are people -- that is, instances of a very specific mental architecture forged by blind evolution in very specific circumstances on this specific planet.
(Last month's started a little late, I thought I'd bring it back to its original schedule.)
A monthly thread for posting any interesting rationality-related quotes you've seen recently on the Internet, or had stored in your quotesfile for ages.