I started quilting only a few years ago and was amazed how quickly my stash began to accumulate and then I was gifted a larger amount. Its very easy to get overwhelmed and I find unless I keep it very organized I don't use it as I should. I forget what I have and then end up buying more. Out of sight can be out of mind and sometimes what you have is not what you want to use. I have quit buying for the most part and only add solids, neutrals and blenders and I am trying really hard to work with what I have first then if after I go thru everything and I mean everything I let myself buy a bit more.
I see others struggle with their stash, can't find anything, find they don't like it anymore or are not using it. I think it depends on the person some like the rush of buying, some will use what they have first and others like to buy as they go and only maintain a small stash. Space, money and your own personality should guide you a bit.
It's really easy to get carried away so I find now I want just a moderate stash that I can keep up with, keep organized :not my strong suit at all, that still allows me to pull a project together. With a smaller stash I don't really feel guilty if I occasionally buy something.