College students may have no concept of how much stuff costs when their parents buy it. But to be fair, I'm in my 40s, and throw out a lot of expensive stuff too. When you're moving house, you're often tired and anxious, and thinking more about the burden of hauling crap around than you are with the price of replacing it. For me, I actually appreciate the forcing function imposed by the size of a moving van or a storage space, it works better than Marie Kondo to help get rid of stuff I've accumulated. I may believe the underlying reasons justify my behavior, but I can't judge anyone else for doing the same thing on the biased assumption that their reasons are less defensible.
I had a bad habit of accumulating stuff that had some abstract value (may come in handy in the future, is a good deal, etc), and letting go of a lot of it was hard in part because of guilt surrounding environmentalism. Even something that I had no attachment to whatsoever felt extremely difficult to get rid of because it needed to be disposed of ethically. The idea "you can't save the rainforest if you're depressed"[0] was helpful to me in breaking out of this mentality.
I have realized that I won't give things up and so I avoid getting things without some surety that I will really want it around for decades. There are a lot of neat toys in the world that I honestly wouldn't have time to enjoy them all anyway so better to focus on ones I really will enjoy.
