There is the aspect that, by wearing a leather or fur coat or whatever, you are normalizing the perception of animals as products to be turned into useful items. That said, I understand people who don't see that as a big enough reason to throw something out and buy a new thing (any production of anything is going to have a negative impact on the world, so using the animal products you have is arguably more vegan than buying vegan products to replace them) but yeah in general this is one of those edge cases where I don't see much urgency in deciding which approach is "correct"