Remorse for not purchasing a 1956 Topps PSA 4 Mantle that was offered to me at a very reasonable price!
I hemmed and hawed too long so the seller, rightfully, sold it before I had made up my mind. I was given more than enough time but I just couldn't pull the trigger based on the U.S./CDN exchange rate at the time and the fact that I struggled with putting that money towards my 52 Topps collection.
Like a fool, I torture myself by looking at it occasionally.