I'm like Koyote. I keep some loaner knives for the purpose of handing out to folks without. Simple reality is most people don't have a knife and if you want to stick with the I won't lend my knives rule, you will be walking a solo path much of the time. It would be nice to live in a world where people respect the same tools that we do, that they have the same values and love of outdoors and bushcraft. Unfortunately, we are the fringe group of this society we live in.
Lend out those loners I say. Better to recruit ten people to our way of thinking even if that means 3 knives return buggered up. In the end, the person who buggered up your knife will learn something. If you act pretty cool about it, try to figure out what they did and correct them, then you'll have both learned something.
I remember I was working with my boss on a net, pulling fish from it. He isn't used to knives and I had my Buck 119 on my belt (this was my main goto knife back then). I was pretty proud of the edge I had just learned to put on it. Anyhow, he asks me for my knife to cut part of the fish's spine off that was so wrapped up in the net. After he is done he turns and throws the knife point first into the sand. Rather than bonking him in the head with a huge carp, I just calmly picked up my knife and calmly said, 'now driving an edge into sand like that really buggers up the edge and this type of knife isn't made for throwing.' He then asked me what made a throwing knife and we got into a discussion about it. In the end, he learned something and later bought himself some Gibbon throwers. I ended up with a dull knife, but recruited a guy to the knife world.