Does security thinking foster a negative attitude? When you're thinking about things in security terms, you think about what would make it fail and what the results of failure are. If you carry that way of thinking into everyday life, it's probable that you would see a lot of things very negatively. It wouldn't necessarily affect you that way, but it would be a strong tide to push against.
Mokalus of Borg
PS - Perhaps it would work out like negative visualisation.
PPS - That is, picturing negatives makes you appreciate your current positives.