Probably once you're buying stuff that often, you have so much stuff that you forget what you already have and end up buying even more.

Some of these are simplifications. Instead of upgrading my 12 year old Canon 6D to the mirrorless ecosystem with all its lenses, I opted for a single handheled camera.

In other cases, I bought alternative devices instead of upgrading within the same platform (my Mac and iPhone are both 5 years old). The alternatives turned out not be compelling enough to fully switch to, but found a niche as purpose driven devices. In many cases distraction free devices.

In some cases, the super upgrade cycle was driven by a desire to finally stop carrying a microUSB cable with me when I travel.

As for the mechanical watches, yes I have too many.