Mistakes I’ve made

Lending out audio gear!

Loaned a turntable to a relative- he tossed it in the trash when he was done with it and switched to cd

Loaned a turntable to a friend- he has no idea what happened to it 

Loaned a receiver and cassette deck to a relative- he bought a mini system and threw out my gear 

Loaned another receiver to a friend- got smashed 

what “why did I do that” moments have you had? 
I borrowed the Ten Years After LP, "A Space In Time" from an acquaintance around 1977.  Saw him at a get together in 2016. 
Then we were all to meet for dinner in 2018 so I brought the LP with me and returned it.  We all got a kick out of it.  It was an early pressing and the sound quality of the LP was exquisite.  
Better late than never.
I loaned out a nice pair of Yamaha speaker's, and never got them back because he moved with them, when i should have loaned him my EX-WIFE and I would have been happy as a fly on shtttt. because she loved to destroy audio gear when she got mad.
I learned not to leave the grills off my speakers when toddlers are in the household. They can’t resist poking the tweeters.