I certainly respect a point of view like HarryT's. On those occasions where I've downloaded books I already own in paper, I've found they are usually scans of a paper version (one can see the OCR errors). Very rarely, the books have appeared to be "cracked" commercial versions. I don't feel comfortable with such a download. Creating a good ebook takes time and effort, and when a company invests that time and effort, it's reasonable for them to expect compensation. When a fan scans a book and makes it available, it's more like a donation to the community, and if I own the paper version anyway, I could have scanned and OCR'd it myself, so I don't feel I'm depriving the publisher of anything, even if they also have a commercial version available.
These days I try to just buy ebooks in the first place, but there are several authors that I routinely share with other members of my family and friends, and most of them don't have ebook readers (and don't like to read on the computer). So sometimes I still end up buying paper. Also, some of the books I want aren't available as ebooks (commercial and/or darknet), so the only way to get them is to buy the paper. But I really prefer reading on my iLiad, at this point. The only circumstance in which I'd rather use paper is for certain reference works, and if search functionalities improve, I'd prefer to read those on the iLiad as well.