As stated there are some drawbacks to buying without a project in mind. My stash started with blenders and white on white or cream on cream... and then grew from there. The neutrals will somehow always find its way into a quilt.. and they are wonderful to have on hand when purchased at the right price.
If you are content in your quilting process... don't feel compelled to have a stash ... there are plenty of us that have fabric purchase regrets.