I don't like to accumulate physical books because they take up space and become clutter.
I like to be able to adjust the font as my eyes aren't that great anymore.
If I want a book, I can just get it without running out to the book store.
I can carry tons of books with me if I'm going on a trip or something.
There are free and very inexpensive books available.
I don't have to worry about my toddler taking out the bookmark. She ignores ereaders but can't keep her hands off a book with a bookmark in it.