I started darning B's socks twenty years ago when we were first married. I did it then because we didn't have much money. Those wool socks he liked to wear were expensive and we wanted to make them last. At first I used bits of leftover yarn. Then, when a pair got too worn for darning I unraveled it and used the leg yarn to darn the other socks.
I enjoy darning the socks because I feel a connection to my ancestors. They were thrifty folk. I also get to use this wonderful darning egg that belonged to my great grandmother. B now wears socks that I knit for him. He likes those better than the store bought as they fit his foot exactly and don't have a seam on the toe. I still darn these socks for him as it is much quicker to darn a hole in the toe or heel that to knit a new pair. He also likes plain "utility" socks which are not the most interesting to knit. I darn his socks so that I can have time to knit socks with yarns like THIS:
I am planning a couple of fair isle pairs for my self. I liked both the top hank AND the bottom with the gold in the middle so I had to buy all three!!! I will get several pair from them.