Yes, but with Kindle at least you can strip the DRM of your eBooks.
There's a Calibre plugin[1] that does it.
If you really care about ebooks that you purchase, I highly recommend installing this plugin. It automatically strips DRM off books you download and open with Calibre.
And keep a back-up of the (DRM-free) books somewhere that's not Amazon / a cloud. Because a cloud is simply a computer that you do not own.
[1]http://www.geoffstratton.com/remove-drm-amazon-kindle-books