I've also read the Nuremberg Diary. That book, and Hannah Arendt's famous phrase "banality of evil" have influenced my thinking in this area. People who do very bad things are not necessarily "less than human" or "exceptionally inhuman," although it's easy to make that assumption.
Anyway, I think the concept of a sociopath is entirely theoretical. Until we can scientifically determine what someone is feeling by hooking them up to a machine and reading their emotions as we present them with various scenarios (i.e. a Voigt-Kampff device) then why even bother throwing around such a sensationalized word?
As far as Madoff goes, I never understood the obsession with branding him as notably evil. He stole a lot of money from a lot of people and lied to a lot of people. But the notoriety of that case has more to do with him being an upstanding member of society i.e. "the last person you would expect" (also the scale of the fraud). I don't believe his theft is morally more egregious than millions of other thefts that are committed every day.
http://www.businessinsider.com/what-a-psychopath-brain-looks...
(And taking a loan from a friend while it was collapsing is a sign of desperation, something anyone could do, so don't quote me that particular interaction.)
It's not 'defending' someone's actions to say that there is no proof of an extreme lack of empathy.
Not an argument.
> And I certainly wouldn't apply it to Bernie Madoff or Holmes based on what I know of their situations.
Not an argument.
If you're going to disagree with someone, generally, some logic as to why is useful, not just "I don't agree". Madoff certainly deserves that label, he ruined lives by running the biggest investment scam in history: he clearly didn't in any way care about what happened to those other people, completely lacking in empathy, they were used and discarded.