I suspect this is the factor. A behaviour that is adaptive in an environment of scarcity becomes maladaptive in an environment of abundance.
When my grandmother was a child, practically the only thing that genuinely counted as "garbage" was ash from the fire. Pretty much everything else had a meaningful value. Scraps of paper could light the fire. Scraps of cloth could make a quilt or a rug. Vegetable peelings went to the pigs and not a morsel of edible food was wasted. Packaging wasn't a word anyone was familiar with, but boxes and tins would be saved for re-use. Furniture was repaired and re-repaired until it was only good for firewood.
A lot of people were essentially raised to be hoarders, either through direct experience or transmission of those values from their parents. That mindset isn't irrational, but it's a poor match for the 21st century. It's all too easy to lose sight of the purpose of those values and hoard for the sake of hoarding.
I think that similar factors explain a significant part of the obesity epidemic. The scarcity-era virtues of clearing your plate and being a generous host become vices in a world of supersized portions and supermarket offers.