It's not a feature of cash that it can be stolen, every object can be stolen. The distinctive attribute is transactions are public and immutable.
A car can be driven by its owner anywhere they like. If someone described a car to you as a suicide box you can crash and die in - you might say yes, the fact that cars can be driven freely by their owners means you might drive into someone else. But that's a consequence of the feature, not the feature itself.
