to kill their own people for power seems to be a lack of empathy
They don't think of them as "their own people." There are tremendous ethnic and/or religious rivalries in those places. If the despot is a member of one group, he'll happily kill off all the members of all the other groups and consider it a great accomplishment.
After all, that's how Hitler worked, the quintessential "evil leader." He was reluctant to kill people he (mistakenly) regarded as Aryans, even in conquered countries like Denmark. But he regarded Jews, Gypsies and Slavs as disposable animals.
But another dimension of this is simply class rivalry. It's been a common theme since the Bronze Age, when the first large concentrations of wealth could be created, that the wealthy people did not regard the poor people as "their own people."
This is why so many Americans are uneasy with the prospect of electing a man who would be the richest president since George Washington (who was astoundingly wealthy). I don't know how many of them could put it into words, or even ponder it consciously, but I'm sure that deep down inside they're worried that a wealthy leader would not care very much about their fate. Most of our presidents have been successful and prosperous, but not so prosperous that they felt a disconnection from their constituents.
We've coined the term "limousine liberal" for people like the Kennedys, who are rich but still regard us all as "their own people." (Or as a cynic might say, "they do an incredibly good simulation of somebody who cares."

) The fact that we need a name for it indicates that it's not a common phenomenon.