You can take physical media out of my cold dead hands
Physical media, unlike streaming can be watched as many times as you wish and can't be pulled at a moment's notice.
I can also show movie for the kids on a long road trip where there is no net access for miles. Not to mention if I have no net access at home (cable will probably be out too) that I can pop in a disc and still watch a movie.
Those two are the biggest reasons I will continue to buy content on physical media.
Sure, streaming is convenient but physical media still has quite a few advantages.