Well for example, say you like to try shooting steel targets at 600 yards. That’s very hard to do. You might want a setup with a longer, say 20”, barrel. The scope you choose would likely be very heavy and expensive. You might select a very heavy bipod or simply use sand bags. You probably aren’t selecting a foregrip, accessory rails and flashlight attachments. Magazine capacity is moot. You’re likely going to want an actual high-powered caliber since the normal AR15 is NOT high powered despite what the news tells you and despite what your emotions tell you when you see one. In this case .308 would be much better but then the gun is termed an AR-10 but it’s basically the same thing.

Now on the other hand you like to enter 3-gun competitions where you’re running to different positions within an obstacle course like setup. (This is essentially just video gaming without the video). In this scenario you’re going to want a very light gun, so no big heavy optics. Instead people opt for these neat little red-dot sites. You may think they’re lasers like you see in the movies but that’s not it. It’s a tube you look through and there is a virtual red dot superimposed on the scene. They’re really neat.

Then you might choose between gas operated feeding and piston driven. Cost, cleaning requirements, reliability all come into play with this choice.

The list goes on and on really. These may not sound like “needs” and you’re right they’re not. This is just a hobby where go out an most commonly shoot paper or steel targets. But it’s a need in the same way women “need” a particular new shoe, or a gamer “needs” a new video card.

Also I hope this explains why people own many guns. Because once you build one for in particular style, you then start wanting one for a different style. Again, think women and shoes. Why do women have many pairs? For precisely the same reason people have many guns.