Like A Train Wreck
"I couldn't take my eyes off of it, as bad as it was. It was like watching a train wreck."
You've heard this. Do you think that person has actually seen a train wreck? How many people can say they were in a position near some railroad track where they spotted a locomotive coming from one direction, then turned to look in the opposite direction and noticed a second train travelling head on towards the first?
If I were in that position, yes, I think I would stand there and watch the scene unfold because when am I going to get another chance to see two trains collide? Never, that's my point. No one sees this happen. It's a theory, an assumption. When someone uses that phrase, they're describing the calamity of a situation is as bad as something they think they would do if put in the position of watching two giant mechanical bodies in high speed motion collide.
It's not so much like watching a train wreck as it is if you were about to see a train wreck, then you think you would stand there and see the whole thing through. That's what captivated you and your morbid fascination which made you decide to torture yourself to the end by whatever it is you're complaining about.
And I'm not so sure anyone not personally tied to the accident, would complain about a train wreck after seeing one.
"That was just awful. The worst train wreck I've ever seen by far!"