I was talking about the anguish of simply having an impact ... What does sustainability matter to the cow you just ate?You've made a number of posts emphasizing that you're not addressing sustainability. In which case: I don't think you're focusing on a particularly relevant part of the discussion.
I see the construction of "having an impact" as a largely irrelevant distraction.
Death is part of the cycle of life. We know that.
Yes, species go extinct. We know that. However the rates vary considerably, and we're at a long-term peak.
As I just wrote in another comment: While moral arguments do get invoked quite a bit, I prefer a more empirical basis for argument. Joshua Greene (http://www.merrimack.edu/live/news/1124-joshua-greene-phd-re...) has some very interesting things to say on moral decisionmaking with which I find myself in generally strong agreement.
For various reasons (and Greene's a neuroscientist who looks as the psychology of moral decisionmaking), we do put an emphasis on people and things who are close to us, both physically and in resemblance (it's easy to feel affection for a tiger or panda than a blobfish or blue-green algae). But in terms of individual choice and having an impact: there's fairly little individuals can do on their own to affect the aggregate outcome.
What you can do -- and some transition / collapse people believe this strongly -- is to take steps to help assure your own individual or tribal (immediate family / community) survival by seeking out viably sustainable areas and lifestyles. The dilemma of personal choice, impact, and action is, I suspect, fairly nonproductive. It imposes a high level of guilt and anxiety without providing much in the way of actual useful productive output. If there's a viable collective outcome it's very likely going to come from some form of collective (or imposed) action.
On the choice thing, I'm finding the RSA Animate presentation I've just been watching "RSA Animate - The Paradox of Choice", by Renata Salecl (http://fixyt.com/watch?v=1bqMY82xzWo) to be illuminating. Choice is, in many ways, oversold. Literally.