I'll add something I haven't seen so far. I am both a collector and user but for different reasons. I use them because they are tools and my lifestyle at home, work, and in the outdoors in my free time dictates that I need a knife quite often and need different knives for different tasks.
I tend to keep knives I use and get rid of a few when they seem to be laying around in the safe too long. Sometimes I buy a particular model just to see it, hold it, evaluate it, then realize it's not for me for one reason or the other. Often times there is a buzz about a model or brand that gets my attention (Busse for example, and Survive!Knives).
Those knives get bought, used sometimes, and then either they become the tool in the stable for a time, or get sold off for something else.
The 'collector' knives fall into two categories. Users and safe queens. The safe queens are just there for whatever reason. They may see me to my grave or get sold/traded tomorrow. The users are a different story. I use them constantly but they are called 'collectors' because they will never be sold/traded. the reason is that most were gifts from loved ones and/or family, mainly my sons. There is no value that can be placed on them and the thought always occurs to me that they will return to my sons some day. I would prefer they are used and have some of my 'soul' in them, rather than just be another knife in a box that 'dad used to own'.