I don't find there is that much convenience on having "hundreds of books in your pocket". Unlike music or films/series, most people are never reading more than two or perhaps three books at the same time and most books take days or weeks to finish (unless you are reading full time). Carrying a kindle is not that much more convenient than carrying a pocket book...

The question is where to store all your physical books though. I own hundreds of physical books (and that's after pruning the collection of books I have no desire to reread at some point). I prefer ebooks now because there's no issue of storage (plus being able to increase the font size is nice now that I'm approaching 50).