The idea that someone could just beat you with a lead pipe until you open up your bitcoin wallet and surrender all the bitcoins and then there is nothing you can do about it in any kind of legal system or even cryptographically should terrify anyone into boasting about having any kind of bitcoin assets.
I wouldn't recommend boasting about owning bitcoin either but why couldn't you involve the legal system? They can go after the criminals who beat you with the pipe just as they could if they beat you to get to your cash/luxury car/art/jewelry/other valuable stuff.