Usually it is for money, jewelry, credit card pins your car...
I think the difference with BTC is that it is quite possible for someone to have quite a large stash on board...
You can't even roam around your city having a few thousand dollars in your pocket if you know either you are famous or you have let people know you are rich and you have money. If strangers, or even people you know personally, know about your finances and financial situation, they would use any opportunity to rob the hell out of you.