GAS, or gear aquisition syndrome.
It is a thing I guess, but I feel, even though my gear stocks are ridiculous at the moment, that it is a thing of my past.
When I got the job with the school a while ago, I was actually windng down, dropping gear and minimalising. Too effectively unfortunately as a lens that would have been realy handy over the last few years, the 12-100 f4, was cast aside too cheaply to be replaced in good conscience and I still miss it.
My needs at that point came down to a little landscape (easily done) and street/travel (same). The school allowed me to shoot in several other fields and my “skeleton crew” got me through, but realistically I knew it was not up to it. I ran scared of very low light sport, indoor horror shows etc, (although I did not realise how close I was to being fine), so I invested in some more specialised gear, explored new software and grew.
I have usually only bought gear recently that I want within the envelope of what I need it, not gear I just wanted without other justification. Examples of this are purchases addressing the need for faster/longer, faster/wider, better AF, lighter weight, weather sealing or actual replacements for the potentially faulty, within which I purchase the best option.
To be totally honest, I went through a stage of hating buying new gear. I would look for fault, talk myself into seeing problems that were not there and generally be unkind to myself and my purchases. Buying to get the job done actually cured that. A mercenary need for tools to do the job helped me move on from a need for precious jewels in a hobbyists kit.