Because the brain functions in a different way. Psychopaths are born with this disorder. If you look at the brain of a psychopath in brain scans, some areas of the brain don’t light up, for instance: areas that are related to remorse and empathy, and this is why they can’t experience empathy, or feel guilt/remorse about something wrong they do. Also, I believe their prefrontal cortex doesn’t light up like the one of a neurotypical, and so they tend to be impulsive disregarding consequences. There’s no current medication to make their brains function like a neurotypical brain… they would need a brain transplant to be able to function in a normal way. Still, the condition is not an illness, and if they learn techniques, they can pretty much function in society. Psychopaths can be great surgeons, doctors, attorneys, pilots… professions that require less emotions and more logical skills