DRM should be banned
The first thing I do when I get an ebook is to de-DRM it, usually using one of the tools available for calibre. I then make an EPUB version in calibre it it wasn't EPUB in the first place, and I copy the EPUB to the Books folder I created on both DropBox and OneDrive. I now have _three_ copies of a DRM-free EPUB. There are multiple readers which can handle EPUB for iPad and Mac and Windows; calibre itself works on Mac and Windows, but not on iPad. (GPL3, I think...) In the event that the original, DRM-infected, copy goes away, I have at least three copies elsewhere and simply don't give a damn. Disk space is cheap and ebooks don't take up much storage.
In addition, I usually don't buy DRM-infected books in the first place. Most of those DRM-infested books are technical books; books for entertainment, I usually get from publishers or authors who go out of their way to NOT have DRM on their books. I reward them for their behavior with money. It is trivial to get de-DRMed books online; certain USENET groups are full of them, for example. My current Strategic Book Reserve has enough books from legitimate sources to last me another decade at my current reading rate, so I have no need to steal books, but I could if I wanted to.