Lack of empathy is the hallmark trait of narcissistic personalities:
Narcissistic Traits
A pervasive pattern of grandiosity (in fantasy or behavior), need for admiration, and lack of empathy, beginning by early adulthood and present in a variety of contexts, as indicated by five (or more) of the following:
Lacks empathy: is unwilling to recognize or identify with the feelings and needs of others
Has a grandiose sense of self-importance (e.g., exaggerates achievements and talents, expects to be recognized as superior without commensurate achievements)
Has a sense of entitlement, i.e., unreasonable expectations of especially favorable treatment or automatic compliance with his or her expectations
Is interpersonally exploitative, i.e., takes advantage of others to achieve his or her own ends
Is often envious of others or believes others are envious of him or her
Requires excessive admiration
Shows arrogant, haughty behaviors or attitudes
Believes that he or she is “special” and unique and can only be understood by, or should associate with, other special or high-status people (or institutions)
Is preoccupied with fantasies of unlimited success, power, brilliance, beauty, or ideal love
Unfortunately as the disorder deepens, it has severe ramifications for the people involved with that person. This guy is the president....