For many it is an unnecessary additional item, for me it's not!
I carry a pocket knife with me at all times - bottle opener, saw, knife, tooth pick, tweezers, can opener, screwdriver, etc. Many call this a multi-tool and the concept of carrying daily is known as EDC (every day carry), much like a wallet, keys, etc. I use my knife daily for one reason or another - peel an apple, open an Amazon box, tighten a screw, etc. But I also carry a knife/multitool everywhere because, hiking everyday, if I fall down a ravine, I know I will be better off with, versus without, it. I will also admit that if on an early morning walk, and I hear a large rustling, it's in my hand or drawn. Why - because I am scared and it makes me feel a tiny bit safer, even though logic informs us that the bear or mountain lion I imagine hearing, will savage me regardless of my knife!
There are a ton of practical uses to carry a knife in the outdoors - food, first aid, convenience, repairs, shelter adjustments, etc. And yes, you might feel 1% safer, and that is fine, but the reality is it is there as a tool and a just in case insurance.