Smajdalf and sterretje may have points of view or opinions, and that is great! However, the point of view of the publisher and copyright laws determine whether a book/music/movie is pirated.
An ebook could be considered more valuable than a printed book because it doesn't take up physical space, doesn't wear out, is easy to enlarge/reduce/change the font, easy to bookmark, highlight, and copy short passages from, and cloud storage/backup of the book is free. Perhaps an ebook should be more expensive than a printed book. In my experience, ebooks are less expensive than the same title in print, in most cases. Does that make ebooks better and cheaper?
A publisher would not have a problem with somebody deleting an ebook from their computer or e-reader. You would have to check with the publisher regarding whether it is OK to then give the e-book to somebody else when you delete it from your own device, because the license agreement may disallow that.