An entertaining thread and somewhat sobering at the same time. I think if most were to take an honest look at their knife stock they might be rather perplexed as to why they have so many items that they really have no use for. We can joke around about "one is none and two is one", but at the end of the day we have to answer for our choices, to ourselves and to those who are closest and perhaps reliant on us.
Whenever this topic comes up (rather frequently I might add) I remember a forum member who whittled away her knife collection down to one knife. As far as I know, she is happy as a clam and hasn't thrown herself in front of a bus because she is down to "only" one knife.
I am happy to report I have not thrown myself in front of a bus, and yes, I'm still happy as a clam having only one knife

My minimalism journey has definitely improved my life. However, it is a continuous process, and it doesn't mean all compulsions go away. I still have one aspect of my life that I haven't been able to fully conquer, and that is my obsession with hats. I still own 20+ and while I do wear them all, I understand that's a ridiculous amount.
Here are some tricks that have helped me counteract the compulsion that others might find helpful:
> Think about what the money could be better used for
> Identify whether the item is a H*LL YES! or not. In other words, is this the absolutely perfect item you've been looking for for years or does it have this aspect and that aspect that doesn't fit your needs or likes as much as you'd want? Simply put, when you already have your needs met, then a new item needs to be a H*LL YES or it's a no.
> Think about the hidden costs of this new item. Will it require upkeep and cleaning? Will it require you to buy other things to go with it or maintain it? Is it going to add more things on your to do list or more clutter in your home, or is it actually going to help alleviate some of those burdens?
> What is the realistic use and intent of this item? Not your fantasy self or some hypothetical future, but what actual concrete needs will it be put to use to tackle?
> Does the want/need of this item actually justify a new purchase or can it be handled by something you already own? For example, if it's a one day a year need, then maybe you can tackle the project with something else you own or maybe rent/borrow one from someone else.
Another thing I try to keep in the forefront of my mind lately is that when I've needed an object, the universe has always provided. None of us is getting out of this alive. Enjoy the journey, and in my opinion, part of the way to do that is to stop spending so much time stressing over a bunch of cluttered possessions.
Yes, own things. Use them. But realize that the illusion of control you feel by owning 5-6 of the same knife as backups is just that--an illusion. The world will quickly show you that you don't have as much control as you think you do whether that might be through a house fire or WWIII or a significant medical issue that leaves you paralyzed or whatever. And if any of those things do happen, having 5-6 extra of a particular knife wouldn't make any of it better for you.