This is a repository for major, life-altering mistakes that you or others have made. Detailed accounts of specific mistakes are welcome, and so are mentions of general classes of mistakes that people often make. If similar repositories already exist (inside or outside of LW), links are greatly appreciated.
The purpose of this repository is to collect information about serious misjudgements and mistakes in order to help people avoid similar mistakes. (I am posting this repository because I'm trying to conduct a premortem on my life and figure out what catastrophic risks may screw me over in the near or far future.)
Even that is less true in the hard sciences. I once had a professor in his mid sixties compliment me for my Clockwork Orange t-shirt after an oral exam, and most of faculty here seldom wears anything more formal than a polo shirt or a pullover.