1) Lost about 20000 Tux coins, by thinking that I backed up the private key while in reality I did not. (I have ~80 different coins) which leads to confusion and management issues sometimes. Tux is worthless as of now, so no biggy.
2) Almost lost my entire password database, thanks god I could find a very old copy somewhere, I don't recall how exactly it happened, probably it was so traumatic that my psyche now blocks the memory access to these addresses.
3) Couple times deleted something with wrong glob expansion, but nothing which couldn't be restored/downloaded again within 1 hour, if I recall corectly I did rm .* instead of ./*
I now have a very ellaborate and unorthodox encryption setup, and I also living on the edge with couple of very old hard drives, I can't decommission them because I'm quite poor. To be continued...