Although I have carried knives just about every day of my life since age 12, I don't think of it as an addiction. Knives have been so useful to me I can't imagine how anyone can do without. My interest in them goes so far as what is good for my purposes and I only have a few on hand, mostly kitchen knives, multi-blade SAKs or Leatherman, and a couple of Spydercos. Typically, I will pick up something if I think it offers some or another benefit, and only if the price is low enough so that if it is not quite right, I can sell it for what I paid or pass it on as a gift. Often, years will go by between purchases.
OTOH, I have an an interest in blades and knifecraft. That's what brings me to this forum. Call it a hobby.