A couple of things...
Caribou fur is different from many animals. The hair is hollow, giving it more insulating properties than many other types of fur. And given the type of ground the animals usually live on, they're hell on knives. I do think we have mismanaged some of those herds and we really need to take a hard look at indigenous people and how many they are allowed to kill.
Secondly, the fur market is pretty lousy today. Most of the fur comes from the mink ranches and many of those have bit the dust due to low prices. Wild fur is no better...When I was a young man, a green-rolled coon hide would fetch over $10 and a properly stretched one would fetch $15+, along with getting a few dollars for the meat (Trivia: Why do you leave one paw unskinned on a coon carcass?) Today, you'd be hard-pressed to get $5...That ain't worth the price of traps and the time it takes.
Fur, if managed properly, is a sustainable resource that will outlast many synthetic fabrics and is superior to most of them in some applications.