Capitalist thinking pervades everything. This anxiety is all about property (even, in some cases, where it's expressed as an anxiety over freedom.) I find this interesting, even more so when you consider that many of these same readers are suspicious of the control exercised by big business, which is a valid concern in socialist terms.
Now, from the perspective of writers, a book or story is the product of their labour and their concerns are around the ways in which this is alienated from them, either by official middlemen or by unofficial ones. This makes perfect sense to me: workers need to eat, and in capitalist societies, they are dependent of the product for this, either directly or indirectly.
But the reader anxiety -- 'I paid for this, so I must own it forever' -- strikes me as both symptomatic of the pervasiveness of capitalist thinking and as slightly illogical, especially when it's on the part of those campaigning against big business. There's a disconnect in the thinking, there, somehow, because the radical ideas are underpinned by a deep-rooted attachment to, and anxiety over ownership. Indeed, on some level, the desire for freedom from DRM -- which I share, btw -- is closely entangled with the same desire for control over a perceived piece of property as fuels the supporters and inventors of DRM, though on an individual rather than a company level.
Capitalist thinking infects everything.
For the record, I discover I don't have a deep attachment to owning e-books. Most of those I buy I read once. In my head they're rather like library books. I don't know why this is. I need to think about that more, clearly.