Why do people get rid of so much stuff when they move?

I recently became addicted to the used furniture section on Craigslist. I found some unique one of a kind items to redecorate my apartment. What I found puzzling is that a lot of people sell a large amount of necessity furniture because they are “moving.” I found that strange because I moved to many different apartments in my lifetime and I usually took most of my stuff with me. Now, I know sometimes, things can’t fit in new places, etc. But it seems like people get rid of many necessary items…like end tables, desks, coffee tables, lamps, bookshelves. Don’t you need these things in the next place that you live? It is so expensive to buy all new stuff. What really puzzles me is the college students that use stuff for less than a year, then get rid of it. This one ad actually said something like” I spent $2000 for this stuff in August the school is over and I am selling all of it!” I was shocked. I couldn’t believe what a waste of money that was. I know they may not have room to store
stuff when they move home or wherever, but what do they do next semester or the next school year, buy all new stuff??? BTW, I used to think IKEA furniture was okay, but when I see how many college students literally throw it away, IKEA furniture just seems so devalued now. Not that it was ever high quality, but it had a cute modern look to it. I guess ultimately my question is, why do people get rid of so much furniture when they move?