For example, if I buy a physical-world object then it's well-understood that the vendor can't break into my house and take it back or, in most circumstances, demand its return. Many physical-world objects additionally come with a warranty assuring that it will continue to work for some length of time.
Online, the digital "object" that I upload to a free service has no such ownership analogue - the service provider can generally cease to offer the service at will. This not only means there's zero warranty, but effectively that service providers can "break into my house" to "take back" the object.
I don't think there's much awareness in the general public that GMail, to pick on a well-used example, could shut down tomorrow and almost every user would irretrievably lose the last N years of their email.