I don't consider GAS a symptom of discontent at all. My personal experience with GAS is that when you don't have something, it is easy to convince yourself that the object of your desire is wonderful and will solve your problems. If you eventually obtain the object and use it, you obtain more information about the object and realise that it has its own set of disadvantages and drawbacks like anything else. GAS is a symptom of lack of real information and your original desire is fueled more by ignorance of the truth and fantasy than analytical understanding. Experience with the object once you obtain it, makes this obvious, this leads to disappointment, and eventually to new GAS for an improved object of desire. The cycle continues.
The only thing that prevents GAS long term is obtaining true information about the whole class of objects of desire in advance, and understanding the advantages of the new thing are not as great as you fantasise, thus saving you lots of money. Perhaps loaning the object for a while.
Personally, I now have plentiful information about the true performance and usefulness of different cameras. I obtained that information and cured GAS by homeopathic means!
Now that I know for a fact what the advantages and disadvantages of many new cameras are, I no longer have the space for fantasies about the imaginary advantages and therefore no longer desire to upgrade. The only remnants of GAS are probably not even to be considered to be GAS, as they are minor practical things like wishing the grip of my camera was a little larger or that the camera could be set to 1:1 aspect ratio. Fancy lenses, more resolution, better features etc no longer have any pull on me. I have gathered enough information from prior purchases to know exactly what benefits and satisfaction will or won't come from satisfying further GAS. And that has done for the GAS. New cameras are boring, just like your old ones.