It is common for a firearms enthusiast to ‘upgrade’ a firearm after they get it. The question is if each change done to the firearm is really an upgrade or not.
Plenty of changes can be made to most firearms to add capabilities, improve ergonomics, etc. However often people are changing things just for the sake of change, or make questionable upgrades that are sometimes downgrades.
Some examples. New Beretta 92FS pistols come with some plastic parts. Some owners on gun forums remove the “cheap junk” plastic guide rod and install a “superior metal guide rod”. The plastic guide rod replaced the metal one as an upgrade because it can flex and still work, while if the metal guide rod gets bent, it can prevent functioning. The plastic guide rod also has clearance space for sand or gunk thus allowing functioning in adverse conditions. These owners are downgrading their pistol while thinking that they are upgrading it. A similar thing is often done with 1911s. For quite some time full length guide rods were considered an almost mandatory upgraded. Now we know that in many cases, you are better off with a standard GI style recoil spring setup. Even with the Glocks, you often see new owners want to “upgrade” the recoil spring guide rod.
With the AR15 and the AK family of weapons owners will often change out furniture, or make other changes to try and achieve a different look. Before spending your money, why not take a minute to consider if you really need that $50 dollar pistol grip, or that $200 dollar butt stock. While most all of these changes are nice, decide if you really need them. Consider if you really want an opposing lawyer showing a jury your pistol with its Punisher logos on it. Will it really be so cool at point in time? Will those aluminium pistol grip be comfortable in hot weather, or when its left out in the sun? Is putting a several hundred dollar quad rail on a rifle you don’t plan to mount any accessories on really worth while?
Make sure that the changes you make to your firearms are actually improvements, not potential problems. Each change should be thought out, and improve either the capabilities, functionality, or ergonomics of a firearm.