For personal consumption? I modify the ebooks I read, changing the font and other formatting, reducing the size of images or removing them entirely, and removi

For personal consumption? I modify the ebooks I read, changing the font and other formatting, reducing the size of images or removing them entirely, and removing advert pages (sometimes, not compulsively). I do this for my own readability preferences (I don't have a formalized disability, just preferences at this point). As I am not reselling the artist's work, I consider this fair use. To what degree am I wrong?