Not necessarily. Note that you take precautions because you foresee difficulties. If you intend to go diving in shark-infested waters... or, indeed, any body of water that might conceivably host sharks... then considering that fact in advance, purchasing shark repellent, and having it on-hand during the dive is totally sensible. If you're going to the South Pole instead, then shark repellent is worse then useless; it's presence will serve merely as additional weight to hinder your progress. The difference is, as the quote suggests, a question of whether you're preparing because you've carefully considered the situation in advance, and determined that the preparation in question is necessary to your task... or whether you don't really have a solid idea of why you'd need to do a given thing, but it seems like something that might be useful for a reason you haven't considered carefully enough to describe in words.