It's interesting that Monster escapes some common neo-noir lists (Grant's and wiki's.)
The neo-noir world has a lot of decadence in it, self-indulgence and a lack of responsibility of the individual. That's because there's no belief in God based upon an accurate understanding of God, no external standard handed down by God that's understood and accepted, and no final settling up, no day of judgment, no fear of God, no or little understanding that God has the say and not mankind. God is seen mistakenly as random forces, and people go on to doubt Him because they see evils and wonder why they're there. But the human understanding of good and evil is limited. God has the say as Job is told and as is made clear in many Bible passages that people find unacceptable. One consequence of God being dead in people's minds is that people manufacture their own ideas of good and evil, their own moralities, the results being manifest in many neo-noir scenarios. The alienation you stress is because of separation from God.
A system like a financial system can be sound basically or unsound basically. Even the sound one can fail because of unsound extension of credit. The sound one will get fixed up in rather short order if its sanctions are allowed to operate and punish the people who made unwise assessments of risk and outcomes. The unsound one will be bailed out by a central bank and then the problems will mount up even more. We have an unsound system right now. Greed is manageable or its effects limited in the sound system, because punishments through losses are rapid and merciless. Greed becomes unmanageable and its effects evermore worse when the players, or some of them, have access to unlimited credit. That's what we have now.
The feeling I expressed in my comments on Margin Call is that the focus on individual greed missed the opportunity to highlight the more important systemic structural failings surrounding bailouts, central banks, and credits being extended to favored parties in huge amounts. The system is unsound. When it crashes, the fallout will be worse than the Big One hitting Los Angeles. It will trace back to greed and powers that should not be there in the system. The roots of that, the history of it, go back a long, long time, and current greed is not the culprit.