I am in serious need of a good organizing, but I can't see getting rid of 80% of my stuff ... or even 20%! Like Liptontee, my stash supply is very small compared to most crafters. And I've bought a few mistakes along the way. I've given away a few things, sold a couple others and made due with what I bought when possible.
A little story ...
More than 15 years ago, I jumped on the D.O.T.S. and Stampin Up card-making bandwagon. Unfortunately, it didn't take me long to learn that stamping was not my thing. (I had no Internet to turn to for ideas; no talent to color my items with the markers.)
Fast foward 15 years ...
After scrapbooking for a couple years, I get curious about Copic markers. I decide to give them a try and love them. And you know what? I'm so glad that I still have those old stamp sets! The ink pads and Marvy markers were no good, so I had to toss them.
Go ahead and purge.
Give away (or sell or whatever) all the adhesive, ink pads, markers and other things that would dry out or go bad over time.
But keep the rest of your purged stuff in a couple of boxes and store them in the garage. Then, in six or eight months go through everything you "tossed" and if you still don't want it or need it, then give it the final heave-ho out the door.