P mentioned yesterday morning that he was taking his wallet with him to school to buy books at the school's book fair. In addition to some cash, he said he had a bunch of gift cards that he had gotten. I asked him why he would carry the gift cards with him. No good reason. That is where he stored them and he didn't feel the school was a dangerous place to take his gift cards to. I said carrying those gift cards around was an unnecessary risk. Hundreds of people attend his school every day, including many strangers. Why take the risk? He continued to argue that nobody in his school would steal them, but the next day told me he had taken the gift cards out of his wallet :-).
I told the boys that when I travel, I make a point of leaving at home unnecessary things that would be problematic or expensive to lose. And when I go on excursions, e.g., a day hike or bike ride, I often just take a bit of cash with me and leave my wallet in a safe place.
You do have to think carefully about what is a "safe place". I mentioned to the boys that soon after graduating from college I decided that my apartment was not a safe place to keep my college ring and nice watch (since I was concerned the cleaning person might steal them). So I decided to store them in my desk at work. Well, that was not very well thought out as they were stolen from there - probably by the cleaning person from the office!