Firstly, innocent children all around the world suffer in ways that are terrible. For example, thousands of children in Africa don't have enough food or water to live, schools or medicine. They are born, and then suffer and sometimes die. Other children live in war zones, like in Palestine or Israel, India, Pakistan or Afganistan, Iraq, as well as other countries in Africa. Other children are born into violent families. Their father may be an alcoholic, the parents may take drugs, live as criminals or just be very poor.These children may be hit often, and maybe they don't know that it is not normal to be hit. They are only children, and have not done anything bad, or wrong, but they suffer.
Secondly, people are born with different abilities, and society rewards some abilities but not others. We can't control which of those 'natural abilities' we are born with. Some high school students can read, understand and remember things more easily than others. Such students may get very good test results even if they don't study much. People with a great ability to sing, play sport, act or write interesting stories can become famous and get a lot of money even without studying at school very much. Other people, who are good at helping old or sick people, or bringing up children or with no single great ability will never receive a lot of things in life. Children of poor parents have less chances to study at good schools or try different activities such as sport or art. Other people are just beautiful, handsome or have voices that other people enjoy listening to. The ability you are born with is just luck, not something you deserve.
Finally, kind, generous people don't live longer or have healthier lives than unkind, mean people. Kind people can get sick or die young in the same way as unkind