These are generally mentally unstable people. I liken it to a young child that wouldn't have come up with the idea - of stealing candy - let's say, until someo

These are generally mentally unstable people. I liken it to a young child that wouldn't have come up with the idea - of stealing candy - let's say, until someone tells them specifically not to steal any candy - i.e. it expands their field of what's possible. Then it's their notion of morality (right vs. wrong) that dissuades them.