My answer is I've bought between 10 and 15 knives to use and find the perfect knife. Of course, the perfect knife came down to two. One small EDC and a larger one for harder tasks. I have a couple that fit both categories. As far as I'm concerned I could sell the others but just don't want to.
Collecting is different. People collect all kinds of things for one reason or another. Coins, stamps, shot glasses, etc. My wife has a glass collection that fills one large china cabinet and three small ones. There always seemed to be another one showing up. Some are cheap, some are not. If she liked something for $1 she'd buy it. I thought that was a good day.
Sometimes they were more than $1.
I don't even want to remember what we paid for the china cabinets. I used to say I was going to buy a china cabinet to put my tools in.
I don't think you'll find a coin collector asking a knife collector "why?". They understand even if they hate knives.
Personally, I'm VERY grateful to live in a country where we can be so pathetically foolish. Sometimes I feel guilty. I never give to charities. I have bought a combo meal for the guy with a "work for food" sign from time to time. One had a dog with him and I was going into Wal Mart so I got a small bag of dog food for him. No people food though. That guy was more grateful than anyone I ever bought a burger for. Sorry, didn't mean to change the subject.