I got my Sony three years ago mainly to be able to read all the free stuff I had collected over the years (the free Hugo and Nebula stories which are posted every year, books from the Baen free library) as well as to be able to read fan fiction without printing it out (I never liked reading longer texts off a computer screen and it is becoming more difficult the older I get).
The ability to increase the font size has become more and more important over the course of those three years.
I have to admit that I only started buying books when I got my Kindle 18 months ago (before that, I think I had bought three or four books from Baen because they were DRM-free and easy to handle). Now I have to control my book buying very much in the same way I had to control it when I still bought paper books.
Do I have to mention that my small apartment is crowded with books? I still buy paper books from time to time though, but mainly nice hardcovers. My TBR is higher than ever now, but I don't bother to count any more.