People are not cruel by nature. Such character traits are acquired as a result of negative experiences with other individuals. They serve as a kind of protective shell for a person who once experienced very severe pain.
For the most part, by nature people are not cruel. They become such as a result of communication and interaction with other personalities. We are all different - someone more sensitive and kind, and someone cold and selfish. We all come to this world to receive certain lessons.
The process of communication is not easy. People, having gone through difficulties and suffering, become soft and warm-hearted, but not all. Someone decides for themselves that if life was cruel and unjust with him, then he has the right to answer with the same coin.
In most cases, the manifestation of cruelty is a hidden inner pain and self-defense. An individual at a subconscious level feels weak, vulnerable and abandoned, but does not want to admit it. He believes that manifestations of cruelty are a demonstration of strength and character.
Also, cruelty can be found in a sufficiently prosperous person in all respects. This happens when a person has not experienced difficulties and hardships in his life. He does not understand that it can hurt another.
Such psychological deviations of the personality as sadism and cruelty are very similar to each other, and often manifest together. This is especially true for teenagers.