Interesting regarding the depression and "saving stuff". My parents lived through the German depression, and in many ways were the opposite, almost going the minimalist route. They were more into "reuse". I think to this day my dad may have some nuts and bolts stored in tin cans from the 60s, so they saved stuff like that and used things until they about fell apart, but they never hoarded anything.
I assume the thought process for US "depression hoarders" is much like that as people who live on rural properties with space - "You never know when you might need that widget, so save it so we don't have to buy one." My parents were all about not getting stuff you don't absolutely need (to the detriment of my childhood re: toys). On the negative side, it was always a struggle to keep my dad from just tossing my "useless" stuff in the trash without asking me first.