His problem, and the same with most criminals, was greed.
He couldn't stop at $50k. Or $100k.. no he wen't up to 800k!
Imagine how many sales he ahd to have made to get that kind of money.
Blatant greed.
I don't let stuff like this stop me from buying something on eBay once in a while (not often though).
I just only buy from people with established credible looking feedback