Just because you don't invite people over to your place doesn't meant that I don't. In fact, I do, regularly.
Also, if you put the pieces together, the fact that you have a device around that you're comfortable reading on most of the time doesn't mean that I do. My phone is a terrible device for reading on (as is my laptop, honestly), and the only one that I have around as often as I have a book in my bag.
Giving someone a book has an emotional connotation that loaning someone something on an electronic service does not. That may change in future generations, but for me, and my ilk (most of whom also don't read books on electronic devices), giving someone a physical book means far more than loaning them something with an internet service.
I have no problem that in your social environment that Kindle books are superior to physical books. But you said that you can't understand why anyone else would prefer physical books, and it seems the simple explanation is that, well, everyone isn't you.