The only time (luckily) i've seen didjit/hand carnage was when i was young and saw a guy cut his fingers badly on a large table saw where i was working. He had been on that saw day in and day out trying to catch them up on some work they needed done there. But, he was getting tired and overworked on the same machine. I'm guessing he was getting a bit hypnotized from the repetition.
I can see that, but, gosh, that chain episode was entirely avoidable. I'm sorry it happened for sure.
I've done some stupid stuff, no doubt, and thankfully wasn't harmed too much.
You just gotta think, take time and think a little!