He has an "entitlement mentality". What this means is that he thinks he is entitled to the good life in general, and unfortunately, also entitled to scam someone, since well, he is "entitled" to do so. This mentality could arise from a misguided notion that he is actually very "good and capable", but because of some misfortune or unfairness or lack of foresight by others, they failed to see his "talents".
You may get to hear his emotional baggage, I emphasize again, when he thinks he is annonymous.
"My family didn't support me, my mother supported my sister more, my former employers never sent me overseas, I have nothing but bad luck, so-and- so didn't recognise my capability, blah blah blah etc etc etc".
Everytime the cunning one logs on with whatever nickname, I'll try to give him (you?) something to read, even if it's not new.
Something perhaps to remind him that his mother and employers saw something in him they didn't trust. Good judgement on their part.
The emotional baggage mentioned above were all things posted by him at one time or another, using different nicknames.
Trying to make the baggage just that little bit heavier.