The thing is that when most people say that there are a lot of scammers here, they're generally wrong- It's the same ones over and over.
Knowing this, there would be a finite amount of scammers, but when more and more start scamming the legitimate people, it's the rage and the whole "I don't even care anymore" feeling that would incline scammers to replicate.
It works similarly to suicide. The pain one feels in the moment before suicide is about a 15 minute window. This window is where they aren't thinking, and they won't give into reason when they're alone. When approached by other people or given reason or incentive to live (To not scam, in this case) they would normally calm down.
The actual kick is when they succeed. It's rewarding for them and they made more than they lost with minimal effort. It would only make sense for them to scam, ban evade, and repeat.
I would also imagine that a scammer wouldn't scam if they hear or speak to the person they scam in a Skype call or anything. There are a number of times where I've been constantly ridiculed over Skype and when I just start to get that dull tone of voice or sounding upset/depressed- It would stop and the moment would get awkward. This is why when I *rarely* trade, I would sometimes request to talk over a call if they're from America and if they seem to be shady, though I would never say that of course. I could always say "It's easy tor record the trade and neither of us have a loss."
I'm pretty sure I was REALLY redundant in my reasoning but that's mostly it.