Someone may correct me if I'm wrong, but my understanding is you don't "own" ebooks in the same manner as a paper book. When you buy you are purchasing a "license" that may be revoked at any time. See below for better a summary. http://americanlibrariesmagazine.org/as ... ing-ebooks
You are correct in most situations that when you "buy" an eBook you have a perpetual license not property, and in most cases this license is not transferable, even to family or your heirs. This is not just eBooks though - also your iTunes music library for example. Whether the license can be revoked at any time is another question... that may not be the case and that may or may not fall afoul of laws regulating commerce.
Some eBook publishers, usually of the more progressive bent (like O'Reilly for tech books), do allow for transfer/resale - it all depends on the license terms.
eBooks licensed for library lending is yet a different kettle of fish with some publishers demanding special terms such as the license expiring after a certain number of loans.