The problem with the conclusion that “power corrupts” is that it’s next to impossible to tease out a casual relationship. Yes, we can see that power and lack of empathy are correlated, but none of the experiments noted in the article you posted can definitively say whether that’s because 1) power makes people lose empathy or 2) unempathetic people are more likely to accrue power. There’s also a contextual factor to consider. Many socialists have argued that capitalism incentivizes unempathetic behavior, and that it is possible to build a system where empathy is selected for rather than selected against. This is also impossible to prove definitively, but if true then it would be the case that the particular lack of empathy we see in many powerful people is specific to our own society, and not to humanity in general.