Try and remember back to the day when you could fit all of your worldly goods into your car and you moved into your first apartment or non-parentally owned dwelling. It was good to have all of that space for yourself and you could never imagine having enough stuff to fill it up.
As you progressed through life you started accumulating stuff. And more stuff. Pretty soon that dwelling was bursting at the seams with your stuff. So rather than get rid of your stuff, you got a bigger place to store your stuff.
Then you had life events (marriage, children, pets, hobbies) that forced you to get more stuff, which filled up your dwelling even faster… so once again, rather than get rid of stuff, you get a bigger place to store your stuff.