If I was in a colder climate, I wouldn't hesitate to use a coat made of fur/animal skin if that is what kept me warm.
IMO, if you are killing the animal for a purpose, it isn't such a bad thing. Making fur coats is a purpose. If there was no fur coat industry, those minks wouldn't be alive. One think I have heard mentioned before, animals that hunters and industry raise or hunt, tend to survive and thrive. Animals they don't want or care about often end up endangered. Attaching value to an animal can help it.