Knife crime? I think not.
I carry a knife which I use for everything out there - opening boxes at work, cutting off that damned piece of fingernail on the end which doesn't want to peel off, shotgunning a beer, cutting a piece of tape, etc.
A knife can be a life-saving device more than a means of lethal force. If someone is wounded and their clothing needs to be removed around the wound, what are you going to do, use a toothpick? Nope, you cut it with a knife.
A knife has also saved me from getting jumped. I got approached by three guys while walking through a rough part of town, they approached me saying "I know this kid got some money on him" and prepared to attack me, when I simply took out my knife, said "back off", and they moved on to find another target. I didn't carry it because I was "paranoid", like the moron Board said, it's because I've had three friends get jumped and beat to a living pulp in the same situation.
I only meet lethal force with lethal force. If someone swings at me, I'm going to clutch an object in my hand to increase the surface area of my fist and strike them to end the incident quickly and without deadly force. If someone pulls a knife out and thrusts or swings at me, I'm going to go for cutting their arm perpendicular to the bone to force them to drop the knife, causing no deadly injury.
As I stated, I have only used a knife once as a means to defend myself when grossly outnumbered, but did not use the knife other than to let those know that I was armed and not to jump me. Had I no knife, I'd be without a wallet and have a broken jaw and a few busted ribs. If you call that being "paranoid", I think you need to review your definition of the word. - you'll see that it's called being "prepared", not "paranoid". Some of us don't live in a gated neighborhood with white picket fence yards. Some of us have to choose between being prepared or being murdered. Which would you choose?
99% of the uses of knives every day are not crime related by any means - just utilitarian uses.