I have three bone-handled Camillus Army Engineer's knives, all of them made in 1942-44. I don't know what they looked like when new, although the knife shown has on all four blades & tools several areas of (presumably) original mirror polish. What that says about the wearability of bone, I don't know because i don't know what this knife experienced.
(The knife has been cleaned up a bit since this image was taken, and the lighting here emphasizes the dark staining on the blades.)
But I also have another nearly identical Engineer's knife where the blades & tools, though use, have taken on a nearly satin finish all over. And the Rogers bone on the handle of that knife looks almost identical to the wear you see here.
Bone wears, but does so nicely in my view. Breakage would mean an epoxy repair, or in extreme cases, setting the knife aside, probably forever.
I think a lot depends on how pristine you want the thing to remain. For me, every knife is a utilitarian object, to be carried and used appropriately and with me paying no particular attention to the accumulating wear and tear until it affects usage. At the other extreme are those with collections of "safe queens" that hardly see the light of day. Everyone finds a happy place somewhere on that spectrum.
With color-anodized alox I have a black Vic Pioneer and a red Classic the accumulated scuffing is simply part of ownership. As someone said elsewhere in regard to military knives, one that shows signs of wear shows history, one that's mint is just war surplus. A scuffed and worn knife of mine tracks my own history in some sense, and if I had one in perfect condition, it would be nothing more than new old stock.