I have a Kindle Fire and download free books only.
Two have not downloaded completely and find it impossible to redownload. So will not pay for books as they may not download completely.
Also hate reading a book and having it shut down because it needs recharging so often.
So I still buy good ol used books the most.
The price of downloading a newer book is equal to buying a hardback book, which I never do anyway. I read way to much to pay for hardback books. I wait for paperbacks to come out then buy them used or at discount stores.