It’s a psychological disorder of some sort. If you’re looking for rational explanations I don’t think you will be able to find any that satisfy you. I’m a bit of a hoarder myself. Not anywhere close to most of the things you see on T.V but I sometimes worry that, if I don’t get a handle on it, I might get to a certain age or a certain point where it will be too late for me to get a handle on it. It is a disorder, bottom line. If you want or expect good reasons for this kind of behavior, then I suspect that you will be either be baffled or disappointed at least.