You're implying that all people are inherently predisposed to evil behavior, but lack opportunity. And that consequences inhibit bad behavior. I've seen little to support those implications. Have you seen otherwise?
Though he didn't say 'all', he said 'plenty'.
I think he maybe has a point, though who knows what numerical value to attach to 'plenty'?
For one thing I notice how people behave when they get behind the wheel of a car. Many people, even generally decent people, do seem to have a tendency to lapse into 'might is right' or 'it's fine if I can get away with it' as their one guiding principle if there isn't outside enforcement of rules. You see it all the time if you are not a driver.
I think it's simply a habit you can acquire if you have power and are able to get away with something for a long time.
Which is why I tend to think power differentials are the real problem rather than the nature of individuals. Power gets abused, it's in the nature of the thing.