I love reading in physical books. However, they're too bulky to carry several around for a trip, bus ride, etc...

So, I love my Kindle because it lets me carry around a ridiculous library in a small form factor.

Yet, I sometimes need to be in just my business wear, so don't have place for the Kindle, and end up reading in a smartphone.

Much like carrying around a dedicated camera has been superseded by cell phones (even though no-one can deny that dedicated cameras take superior photographs), paper books are superseded by e-book readers, tablets and smartphones, because of the convenience factor.

And, as you say, they have to compete with apps, the Internet, etc...