Not viewing communists in the same light as other extremists. Eventually we well be doomed to repeat this mistake. Its results in the death and oppression of millions and it will do again
Reproducing.
Not quite “man” made but, to quote Douglas Adams: “In the beginning the Universe was created. This has made a lot of people very angry and been widely regarded as a bad move.”
Failing to take decisive, systemic action to address climate change.
Twice rejecting Hitler for art school. Damn you Academy of Fine Arts Vienna.