Let's imagine you could kill people and make a profit from it. Not only were there no negative consequences to killing people, there was an economic incentive. Would you do it?
Maybe, maybe not. You're a moral person; you read your Bible; you know that killing is wrong. For most of us, the moral disincentive to kill would outweigh the economic incentive to kill. Even in the absence of materially negative consequences--jail time, our own potential execution--the negative effect on our consiences would be sufficient to prevent most of us from killing.
But let's imagine that economically profitable, consequence-free killing had been the social norm for 200 years or more. Might the situation be different then? Might not many of us be socially conditioned to accept killing-for-profit as a positive good, or at least an inalienable right? Might not many of us ignore the Bible (or whatever religious or ethical text we currently subscribe to) in light of the powerful cultural message that killing for profit is a-okay? Indeed, might not the Bible itself have been rewritten--or never written at all--to sanction such killing?
To help answer these questions, let's consider a real-life analogy.
For the past 200 years or more, it's been socially sanctioned, wildlly profitable, relatively cheap, and (at least as most of us imagine it) absolutely risk-free to burn fossil fuels. And guess what? The vast majority of us burn fossil fuels like there's no tomorrow.
Maybe this is a bad analogy. Maybe gutting the earth, poisoning the soils and waters, devastating habitats and their inhabitants (both human and non-human), and pumping pollutants into the atmosphere isn't comparable to kiling other human beings.
But if you look at all the costs of fossil fuel extraction and consumption, they're pretty significant. The only problem is, these costs don't strike us as costs, because they're "externalized"--they're not built into the market price of the thing. Health care costs, loss of species and habitat costs, community degradation costs, planetery climate collapse costs aren't reflected in the price we pay at the pump, so we get to engage in incredibly risky, damaging behavior without (apparently) suffering any negative consequences for it. Quite the contrary, we benefit from it economically (some of us, such as BP executives, more than most, but all of us to a considerable degree). And as a result, most of us engage in this behavior--a lot--without a second thought.
All of which suggests not only that we're incredibly malleable beings, capable of being socially engineered for better or for worse, but that if we're really serious about getting a handle on our current bad behavior, we need to acknowledge it as such. Even if doing so might prevent us from making a killing.