I can think of several situations where I would lend a knife-
I'm a "knife person", but on a few occasions in my life I have forgotten to take a knife with me when going out. Even a lifelong "knife person" can forget. If I forgot to take a knife and needed to cut something, I would certainly appreciate it if someone were willing to lend me one. So I'd do the same for others.
If someone flew in to visit me from out of town and didn't want to check a bag just to bring a knife, I would lend them one while they were here.
If a friend and I were working on something together and my knife were better suited for a task than his knife, or he didn't have one, I would lend him one of mine.
If I were on on a hunting/fishing/camping trip with a friend or family member and they misplaced their knife, I'd lend them one of mine.
I was on a date and the woman asked if I had a knife she could borrow to cut one of those plastic string tag holders off her jacket sleeve. I offered to cut it for her, but she said she could do it. So I lent her the little pocket knife I was carrying. She said that she normally carried her own but she forgot it. It was in her regular-carry purse, and she was carrying her date purse.
And then there are emergency situations-
I've seen car wrecks where a person was trapped by their seat belt and random people who gathered to help, and even first responders didn't have a suitable tool to cut the person loose, and called out for a knife. In such a situation I wouldn't hesitate to hand over a knife. I certainly wouldn't insist that everyone move aside and let me do the cutting.
If someone were actively engaged in trying to save someone's life and needed a knife, I'd hand over my knife, even if it were my most prized possession.
As far as non-knife people-
If I didn't know how someone might treat a knife, and if I had a knife that I didn't care about, I'd lend it to them. Meh, why not.
Although I believe in owning and carrying knives, I don't hold it against other people if they don't. At the very least, if a person recognizes the value of a cutting tool enough to ask to borrow one (rather than using their teeth, house key, etc), that's something I can respect. And depending on what they wanted it for, and the knives I had available, I might be open to lending them one.
Who knows, perhaps lending a knife to a non-knife person might actually turn them into a knife person. How many times have you let a non-knife person look at, or handle your knife and they were so impressed by it that it turned them on to knives and they became knife people.
Of course, I would never loan, or even let a person handle one of my knives if I thought they might do something stupid with it that could cause harm to them, myself, or others.