Is it laziness, or do some threats just don't appear very likely to us, even if they are? We tend to feel save in our cars, yet accident and fatality statistics show we probably shouldn't. Moreover, the longer we get away with a behavior, the more confident we are with the way we do things. I tend to become comfortable around dangerous activities, such working with chain saws. I am not oblivious to the inherent dangers, but I admit, it takes a conscious effort to put on all my safety gear before I use my saws. The effort seems more burdensome if I intend to only saw for a very short period of time, or if I paddle that same stretch of the river I have paddled so often. A very short sighted type of cost-benefit analysis, I am sure I am not the only one guilty of.
Luck is when preparation meets opportunity. I suppose un-luck is when preparation wasn't as good as it could have been. I suppose at the end it all comes down to judgment, but I know I'm in no position to through stones...