What's the most expensive item(s)/ things that has been stolen from you?

Maybe I’m too careless, so I’d like to get a few insights on when others have had things stolen from them.

For example, if I were to go swimming in a public pool, I wouldn’t mind leaving all my things on a chair by the pool.

Or even, in a public library, I’d leave all my books, jacket, and backpack out while I go to the food court (connected to the library) to grab a booster juice.

Or another example—> I’ll be going skiing tomorrow, and I think I’ll be leaving my gym bag with my wallet (containing my debit card, and Drivers license, health card, University ID card, and cell phone unguarded)... I doubt my things will be stolen, only because I trust people won’t go snitching through my things… I’ve never had anything stolen from me from my carelessness so far… maybe I won’t be so lucky. Actually, this does sound very risky… and I’ll definitely be away from my belongings longer than in a swimming pool, or to grab a booster juice.

Sometimes I do secure my stuff in lockers and such, but for tomorrow, I feel that the things I have in my gym bag I will need. Such as money for lunch—I don’t have good pockets to keep that with me, and I need my cell phone to contact the other people I’m going with, but I don’t want to ski with those things either. Or if I get too hot, I’ll want to grab my hoodie in my gym bag, and take off my jacket to leave there.

So, try to change my ways by sharing some stories. Has there been a time that you left your books, or jacket or anything out, and then come back to see that your goods have been stolen? How important was it to you? What do you do now to keep your things secure?

Some more background information: I live in a somewhat “small” city. Not so small that everyone knows each other, but it only takes about half an hour to get from one end of the city to the other… maybe the size of my city has something to do with how I secure my things when going out.