While I agree with you that the system itself inevitably causes these issues, I don't see how this absolves those who use anti-social investment strategies etc. of selfishness. On an individual scale they're still making morally bad decisions, and worse: they're actively influencing the system to exacerbate these mechanisms.

Perhaps, certainly even, but that's not a really interesting way of looking at things. And individual blame is often used as a substitute to systemic analysis of issues.