When I first started to quilt about 10 years ago, I started building a stash because that seemed to be the thing to do. Then after a few years I became very conscious of the amount of money tied up in all this fabric that wasn't being used and decided to stop buying without a definite project in mind. I was encouraged in this decision when someone I knew who liked dressmaking died of cancer in her early 60s and the friends clearing her house found lots of beautiful dress and suiting fabrics that had never been used - how sad that she never got to enjoy garments made from them.
I've not completely stopped "stashing" - if I find a truly unmissable bargain I might succumb, usually for potential backing fabrics, as the backing can add so much to the cost of a quilt - but on the whole I buy when there's a need - and that is such fun, because it's a treat that doesn't happen very often.
My decision was also driven by financial constraints - I just can't afford to buy fabric or anything else if it's just going to sit around. If I had more spare money, maybe I'd indulge in fabric buying more often - but I don't think so. As I get older I increasingly find that I only want to have what I need - too many possessions are a burden.
I know that this is very much a minority view among quilters, and I'm sure I'd be GREEN if I saw some of the stashes described here!
On the other hand, the issue of UFOs, projects that never get finished, is another matter entirely, and that's where my weakness lies!