A study performed at the Faculty of Economics and Management in Magdeburg confirms my intuition that nearly half of all humans are inherently unempathic, even downright evil, but simply hide their psychopathy most of the time, because civilization expects that from them:
The Pleasure of Being Nasty

We introduce the joy-of-destruction game. Two players each receive an endowment and simultaneously decide on how much of the other player's endowment to destroy. In a treatment without fear of retaliation, money is destroyed in almost 40% of all decisions.
See Figure 1 - Destruction frequency over time. At least 25% of people will cause gratuitous harm to a random stranger if they can do so at no cost, while up to 50% will do so if they can also deny it.