When people use someone for their own gain and hurt them, where do their moral values and empathy go?

Maybe they don't have questionable moral values and limited amount of empathy. Some won't hesitate to call this kind selfish or bad. But who to judge? Different people have different standards. Some people worship and practise "the survival of the fittest". They have chosen a mindset and a way of life on their free will. As a by-stander, you can only watch and hopefully you can draw boundaries to against people of that kind. You can judge them but reserve the judgment to yourself if the situation is under control. Then you know what they are and you don't need to join them.