If you remember buying your first DSLR, you probably can also recall your thoughts and the research you did. You can graze the Internet, find most anything about any camera and read reviews before making a decision.
After finally making up your mind and paying for the camera, you wait for the delivery. Until the camera arrives, you have difficulty concentrating on anything else, except for package tracking.
There is a moment or two, between paying for the camera and taking delivery, when you wonder whether you made the right choice. Then, the camera arrives and, after taking it out of the box, you examine all the knobs, dials and menus.
The first phase of ownership lasts but a brief time — only a few weeks. You become acclimated to the placement of the controls and the fit of the camera to your hands. Initially, you shoot for the pleasure of photography and also to test the new addition.
As you meet other photographers and peers, you describe to them the merits of your new baby — shutter speed quick enough to capture a Higgs boson  and video capture quality to make James Cameron proud — and everything you are planning to to do with the camera.
That’s on the outside. The inner photographer uses these facts and hyperbole to validate their purchase.
Once you’ve used the camera for a while, it becomes an extension of you. All of the controls are right where you expect them to be, and the camera’s performance (hopefully) meets your expectations.
It’s here where you really determine whether this new camera is worth the money you spent. If your results show a smidgen of improvement over what you’ve done in the past, you attribute it to the new camera, of course.
You don’t consider that your personal photographic expertise might be improving, too.
On the other hand, maybe the images don’t show an improvement — and experimenting with advanced features consistently produces unacceptable pictures. You blame the camera. Sure, you saw examples when researching the purchase, but your images don’t compare.
That &%*#@ camera! All the advertising was just hype.
Could it be your failure to understand and learn how to use these new features? No, of course not. It’s the camera.
It’s always easier to blame the object and not yourself. If you ever hit your thumb with a hammer, it’s always “that &%*#@ hammer!”
Things have changed and you are ready to consider something newer — maybe somewhat more shapely or with added features. You are face to face with temptation; comparing a recently released camera’s sexy new features to yours produces a sense of seduction.
You step back and try to think rationally: Do you really need those new features? This is more tricky than it appears.
If your current photography has a clear and present need that gear might address, then, of course, the new camera must be considered. On the other hand, the lure of a new camera’s abilities can outweigh any sense of moderation.
In justifying the purchase, are you painting targets around arrows?
For some of us, spending money on a new DSLR is an expensive treat. For others, it’s purely a business decision. Either way, sometimes you just want a new camera — and that may be the only rationale you need.