What do you mean? Ebooks don't get consumed, they don't degrade. And how you sell it is quite obvious. Like you said, the new person possesses it and you no longer possess it. Give them the file and delete any temporary copies you may have.
That isn't an analogous scenario. The problem with trying to compare physical and virtual goods is that, for virtual goods, transferring requires copying. There is no way to transfer an electronic data file without copying it in some way. Until such a process is developed, analogies between physical and virtual goods will always be flawed.
