Fraud and abuse.
Treating Amazon like a mail-in library for books, tools, and other products is the easiest way.
Returning a huge number of your orders regardless of other forms of abuse.
Contesting valid CC charges.
Etc.
> I posit that someone who's banned from shopping at AMZN is more dangerous than someone who plays card games with a dark sense of humor.
I wouldn't necessarily say "dangerous". Maybe "untrustworthy" or "lacking in good judgement" or "lacking a strong moral compass".