The reason that they are his top advisors is that they are like-minded to Trump. They may not have been as totally lacking in empathy as their leader, but they soon realized that is what it took to keep their jobs. They came in with the propensity for non empathy and was given a free ticket to expand it.

In many ways it's not too unlike the leadership in the Nazi Party during WWII. They were all like minded and devoid of empathy.

I have a firm opinion that lack of empathy is a defining characteristic of Trump voters. Almost none of them would vote for him because he did anything for anyone else, unless they happened to identify themselves as part of the same group as those people. Ie. It's basically selfish self interest which Trump takes a level further with his rabid narcissism.