We're talking past each other by using differing definitions of "value". Economic value is affected by scarcity (and other factors).

But I have been talking about ethical value--the thing that classical utilitarians talk about when they say that happiness is valuable. A classical utilitarian doesn't care about whether wolves are common or scarce; they care about how the relative scarcity of wolves makes people feel.

Put another way, I've been talking about terminal values, which are not in any way fungible. I think you've been talking about instrumental values, which are. Is that at all right?