My mother's stash and mine started with leftovers from sewing projects for the kids and grandkids. It was a way to use up those scraps and make something useful out of them. Then the quilting bug bit us and we bought pieces to go with our leftovers, and then had leftovers from the pieces we bought and it just went from there. I have cupboards (plural) full of fabrics and it is wonderful to go to the and pick out what I want at 11:00 at night or very early in the morning. I also have a stash of thread and other quilting supplies that is always available to me. Occasionally I buy new fabric if something strikes me but I am trying to use from my stash as much as possible. The fabric was a lot less expensive when I bought that and I feel faint when I see the new prices on the new fabrics. It is not necessary to buy just for your stash, but buy when you need it and if it is something you really like and a stash will take care of itself.