It is one thing to account for worst case in one's thinking and quite another to live as though the worst case is certain and immanent.
I've posted it here before, but here a quote from a person who had every reason to live a life of fear, and who puts to shame those who live in fear and yet call themselves "jocks" of one sort or another:
Security is mostly a superstition. It does not exist in nature, nor do the children of men as a whole experience it. Avoiding danger is no safer in the long run than outright exposure. Life is either a daring adventure, or nothing. To keep our faces towards change and behave like free spirits in the presence of fate is strength undefeatable. ........ Helen Keller